(CNN)Emmy Rossum is saying goodbye to "Shameless."

(CNN)Emmy Rossum is saying goodbye to "Shameless." The actress announced in an emotional Facebook post that the upcoming ninth season of the series will be her last. "Until 'Shameless' came into my life 8 years ago, I led that kind of transient wonderful life of an actor. And I never realized how much I actually craved the kind of continuity that this show has given me," she wrote. "See, in real life, unlike Fiona, I'm an only child. I never had a big family. Being ensconced in that messy Gallagher family love is something I'd always dreamed of." Rossum has played Fiona Gallagher on the Showtime series since 2011. She co-stars on the show with on-screen patriarch William H. Macy and an ensemble of young actors who play her siblings. "The opportunity to play Fiona has been a gift," Rossum added. After Rossum broke the news on her Facebook page, executive producer and showrunner John Wells promised "a Gallagher-worthy sendoff for Fiona that honors the great work Emmy has done." Wells said the cast and crew are currently working on the Season 9 finale. The first half of Season 9 premieres in September, with the finale set to air in March 2019. "It is always bittersweet when an ensemble member decides to move out of the proverbial house, but our door will always remain open for Fiona to return home for a visit, or to move back in," Wells wrote. "I look forward to continuing the stories of this wildly unpredictable family and all of us on 'Shameless' will miss Emmy and her wonderful Fiona." According to Warner Bros., which produces the series, Rossum is leaving to explore "the next chapter in her career." Rossum's time on "Shameless," while critically hailed, never materialized any awards recognition for the actress. The show afforded Rossum a chance to step into the role of director for the first time. "I am a great believer in: You should know what you don't know," she told CNN last year. "I still don't know a lot, but this is just the beginning of me figuring out what I don't know, I guess." It is not known whether "Shameless" will have a Season 10. It was officially picked up for Season 9 in November of last year. Rossum, however, seemed positive about the possibility of the show's future after her departure. "I know you will continue on without me, for now. There is much more Gallagher story to be told," she wrote on Facebook. "I will always be rooting for my family. Try not to think of me as gone, just think of me as moving down the block."

Obama, World Leaders Urge Action on Nuclear Security, Terror

World leaders declared progress in safeguarding nuclear materials sought by terrorists and wayward nations, even as President Barack Obama acknowledged the task was far from finished.

Closing out a nuclear security summit on Friday, Obama warned of a persistent and harrowing threat: terrorists getting their hands on a nuclear bomb. He urged fellow leaders not to be complacent about the risk of catastrophe, saying that such an attack by the Islamic State or a similar group would "change our world."

"I'm the first to acknowledge the great deal of work that remains," Obama said, adding that the vision of disarmament he laid out at the start of his presidency may not be realized during his lifetime. "But we've begun."

Despite their calls for further action, the roughly 50 leaders assembled announced that this year's gathering would be the last of this kind. This year, deep concerns about terrorism were the commanding focus, as leaders grappled with the notion that the next Paris or Brussels could involve an attack with a nuclear weapon or dirty bomb.

Obama said of the terrorists, "There is no doubt that if these madmen ever got their hands on a nuclear bomb or nuclear material they most certainly would use it to kill as many innocent people as possible."

So far, no terrorists have obtained a nuclear weapon or a dirty bomb, Obama said, crediting global efforts to secure nuclear material. But he said it wasn't for lack of the terrorists trying: Al-Qaida has sought nuclear materials, IS has deployed chemical weapons and extremists linked to the Brussels and Paris attacks were found to have spied on a top Belgian nuclear official.

Throughout the two-day summit, growing fears about nuclear terrorism tempered other, more positive signs of the world coming together to confront the broader nuclear threat.

The U.N. Security Council members who brokered a sweeping nuclear deal with Iran held up that agreement as a model for preventing nuclear proliferation, as they gathered on the summit's sidelines to review implementation of the deal.

Obama also spent part of the summit huddling with the leaders of South Korea and Japan about deterring nuclear-tinged provocations from North Korea, in a powerful show of diplomatic unity with two U.S. treaty allies. Similarly, Obama's sit-down with Chinese President Xi Jinping offered the two strategic rivals a chance to illustrate mutual concern about the North, a traditional Chinese ally.

Undeterred, North Korea only hours later fired a short-range missile into the sea and tried to jam GPS navigation signals in South Korea — precisely the kind of act that South Korean President Park Geun-hye had warned would trigger even tougher sanctions and more isolation.

Aiming to show concrete action, leaders came to the nuclear summit with commitments in hand, known in diplomatic-speak as "gift baskets."

Latin America and the Caribbean are now free of highly enriched uranium, the White House said, praising Argentina by name for converting its remaining stockpile into a less dangerous form. Fissile materials like highly enriched uranium and separated plutonium are necessary ingredients to make nuclear bombs.

The United States, in newly declassified statistics, said its own national inventory of highly enriched uranium has dropped from 741 metric tons two decades ago to 586 metric tons as of 2013. And the U.S. and Japan announced they'd finished removing hundreds of kilograms of weapons-grade material from a Japanese research reactor, and pledged to do the same at another.

On the global front, a strengthened nuclear security agreement was finally poised to take force, extending safeguards for nuclear materials being used, stored and transported while requiring criminal penalties for nuclear smuggling. Those tweaks were approved in 2005, but have sat dormant awaiting ratification from a critical mass of nations, reached only in the past few days.

Still, frustration over the slow pace of reducing nuclear stockpiles shadowed the summit. The absence of key players — especially Russia — further underscored the lack of unanimity confronting global efforts to deter nuclear attacks.

After six years of prodding by Obama and others before him, the global stockpile of fissile material remains in the thousands of metric tons. What's more, security officials warn that the ingredients for a "dirty bomb," such as cesium and cobalt, are alarmingly insecure in many parts of the globe.

Ahead of the summit, fewer than half of the countries participating had agreed to secure their sources of radioactive substances, which are widely present in hospital, industrial and academic settings. Obama said as the Islamic State is squeezed in Syria and Iraq, the world must anticipate it will lash out elsewhere, citing recent attacks in Belgium and Turkey as examples.

Obama has held four such summits in hopes of advancing the disarmament goals he set at the start of his presidency, when he declared in Prague that nuclear weapons were "the most dangerous legacy of the Cold War."

"This summit is not the end of our quest to make the world safe from nuclear terrorism," Prime Minister Mark Rutte of the Netherlands said. He said the assembled leaders were passing the baton to international organizations. "Should the need arise, I know that everybody here will be ready to return."

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Associated Press writers Bradley Klapper, Matthew Lee and Matthew Pennington contributed to this report.

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Reach Josh Lederman on Twitter at http://twitter.com/joshledermanAP and Darlene Superville at http://www.twitter.com/dsupervilleap.

Help Wanted: Trumps Seek Foreign Workers for US Businesses

As a presidential candidate, Donald Trump has made protecting the American workers and bringing jobs back to the U.S. central to his campaign pitch.

“I will be the greatest jobs president that God ever created. I tell you that,” Trump first declared last June when he announced his presidential bid. “I will bring back our jobs from China, from Mexico, from Japan, and other places.”

But in business, Trump and his family have made it a practice to manufacture much of their family-branded merchandise overseas and employ foreign workers in their stateside businesses.

In what has become one of the prominent examples of Trump’s use of foreign workers, his Mar-a-Lago Club in Florida has sought U.S. Department of Labor permission to hire foreign workers to fill seasonal jobs as housekeepers, cooks and restaurant wait staff.

But it’s not just Trump’s Mar-a-Lago Club that relies on foreign labor. So, too, does Trump Vineyard in Virginia, which is run by Trump’s son Eric.

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U.S. Department of Labor documents show that the vineyard has sought approval to hire as many as 19 foreign workers under temporary H-2A agricultural visas for this year’s five-month growing season.

The application states that Trump Vineyard specifically sought “foreign non-immigrant workers” as farm workers because it anticipated “an insufficiency of qualified U.S. workers to meet these seasonal labor needs” and lists an hourly wage rate of $10.72 an hour for a 40-hour work week.

For his part, Donald Trump has defended his hiring of temporary foreign workers at his Mar-a-Lago club, saying it’s “almost impossible” to find Americans to fill the jobs.

The foreign workers are permitted at the club under H-2B visas, which allow employers to temporarily employ foreign workers for non-agricultural jobs when the employers can show an anticipated shortage of willing and able U.S. workers to fill the jobs.

From 2013 to 2015, 250 job openings have been posted for the club’s 8-month-long peak season, according to the U.S. Department of Labor. Only four of those jobs have been filled by American workers.

All of the temporary Mar-a-Lago job postings for 2015, which are for the 8-month-long “peak-load” season are listed as full-time with 35 hours a week hourly wage rate for housekeepers is $10.07, $13.01 for cooks, and a $10.99 hourly rate for waiters and waitresses and no tips.

Neither the Trump campaign or the Trump Organization responded to ABC News' requests for comment

State Department Halts Its Clinton Email Investigation, Defers to FBI

The U.S. Department of State has halted its internal review of Hillary Clinton's most sensitive emails until the FBI's own investigation is complete, the State Department announced today.

"We do not want our internal review to complicate or impede [the FBI probe]," spokeswoman Elizabeth Trudeau said. "We are prioritizing the law enforcement investigation."

In January the department revealed that during its review of Clinton's 52,000 pages of private email it had come across 22 documents that had to be upgraded to "Top Secret" and totally withheld from public release. It said at the time that it would conduct a separate internal review to determine if the secret information in those emails had been mishandled at the time the emails were sent.

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Today the State Department said it is deferring that judgment to the FBI, which is conducting a more comprehensive security review of Clinton's email. The outcome of that investigation is highly anticipated amid the 2016 election cycle. Clinton has said she is confident that will not happen and that she did not break any laws with her use of a private email server during her tenure as secretary of state.

A department spokesman said it is standard practice to allow a law enforcement agency to first complete its work before any parallel investigation is done. Trudeau called the move announced today a prudent "procedural matter."

In March the FBI responded to a formal inquiry from the State Department about how it should proceed with its internal review. It recommended that the State Department follow standard practice and put its investigation on hold.

The State Department has not ruled out conducting its own review after the FBI investigation is complete, with Trudeau saying her agency will "reassess" at the appropriate time.

The FBI is expected to interview Clinton's closest aides and the presidential candidate may also be part of its investigation. It's not clear when the investigation will be completed. The FBI has not formally named Clinton as a target and she has not been accused of any crimes.

ABC News' Mike Levine contributed to this report

The 5 Biggest Things to Watch For in the Presidential Race in April

The month of April appears to be do-or-die for Ted Cruz and Bernie Sanders as both presidential candidates try to win as many delegates as possible and prevent each of their party’s respective frontrunners from winning the nomination outright.

Meanwhile, those frontrunners –- Donald Trump and Hillary Clinton -– will be looking to move further in the direction of locking things up over the next four weeks.

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With so much on the line for every candidate, here are five things to watch for in April:

Will Wisconsin Reject the Frontrunners?

On paper, Wisconsin Republicans are tailor-made Trump supporters.

In the 2012 Republican primary, exit polls showed that 57 percent of voters lacked a college degree.

However, Wisconsin Gov. Scott Walker’s recent endorsement of Cruz, just two weeks before the Wisconsin primary, has given the Texas senator some much needed momentum. In the latest Marquette University Law School poll, Cruz led Trump by 10 points.

The same poll indicates the Badger State is feeling the Bern. Sanders is locked in a tight race with Clinton among likely Wisconsin Democratic voters: 49 to 45 percent.

The Sanders campaign also just announced that it raised a staggering $44 million in March.

I Love New York

New York’s primary on April 19 is not only a battle for gaining delegates, it’s also personal.

Both Democratic candidates have ties to the Empire State, making the contest more competitive. Sanders is Brooklyn-born and Clinton was the state’s senator for eight years.

Having grown up in Queens, New York is Trump’s home turf as well.

Trump was far ahead of Cruz and Kasich in a Quinnipiac poll in New York released on March 31. Trump leads with 56 percent support, while Cruz and Kasich are neck-and-neck at 20 and 19 percent respectively.

The same poll shows, Clinton is 12 points ahead of Sanders.

The Democrats will be vying for 291 delegates while the Republicans will duke it out for 95 delegates.

Ninth Democratic Debate?

There could very well be another Democratic debate ahead of the much anticipated New York primary.

Sanders’ campaign manager Jeff Weaver says both candidates should offer their final pitches to the “critical” voters of the Empire State.

“The people of New York, the largest April primary, deserve to have the debate held in their state,” Weaver wrote, adding a jab at Clinton: “Your campaign has consistently chosen to deny the people of New York the opportunity to see Senator Sanders and Secretary Clinton debate.”

Clinton campaign spokesman Brian Fallon said his candidate would be happy to debate Sanders this month.

"Our campaign indicated to the Sanders campaign through the DNC that we're perfectly willing to debate in April,” Fallon said Tuesday in an interview on Bloomberg’s “With All Due Respect.” “If they can find a mutually agreeable date in the next couple of weeks before New York, I think it could happen.”

April 26: The Big One

Five northeast states will cast their ballots on April 26 -- Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island.

Some 463 delegates are at stake for the Democrats and 172 delegates for the Republicans.

While nabbing a majority of the states would give Sanders an opportunity to catch up to Clinton, who leads the Democratic race with 1,243 delegates, candidates on the other side of the aisle seem to have more at stake. For the Republican Party a majority of these primaries are winner-take-all or take most contests.

Delegates, Delegates, Delegates

As of right now, Trump needs to win 60 percent of the remaining delegates in order to garner the needed 1,237 delegates to clinch the Republican nomination. Should the bombastic billionaire lose Wisconsin by a huge margin, a contested convention is almost guaranteed.

With that in mind, all eyes will be on local state meetings where the actual individuals who fill the delegate slots will be chosen. These people will be critical when they are free to vote however they want on later ballots of a convention.

Clinton needs to win just 671 more delegates in order to be the nominee of the Democratic Party. Sanders would need to win more than twice that amount of delegates -- 67 percent of the remaining 2,042 -- to be the party’s standard bearer.