Homeland Security Secretary Janet Napolitano will resign her Cabinet post to become the next president of the University of California system, administration officials said Friday.
Napolitano's departure comes amid a high-profile legislative push for comprehensive immigration reform.
During her time heading the DHS, Napolitano has been a vocal proponent of the legislation, which would provide a pathway to citizenship for those already in the nation illegally, touring border areas and lobbying lawmakers.
Napolitano has also been a frequent target of conservatives, who have criticized the DHS on a multitude of issues, including its decision to impose more invasive searching procedures in airports after a failed terrorist attack.
In a statement Friday, Napolitano said her tenure had been defined by working with President Obama and the staff of the DHS to "minimize threats of all kinds to the American public."
"The Department has improved the safety of travelers; implemented smart steps that make our immigration system more fair and focused while deploying record resources to protect our nation’s borders; worked with states to build resiliency and make our nation’s emergency and disaster response capabilities more robust; and partnered with the private sector to improve our cybersecurity," she said.
"I thank President Obama for the chance to serve our nation during this important chapter in our history, and I know the Department of Homeland Security will continue to perform its important duties with the honor and focus that the American public expects."
President Obama heralded Napolitano's "outstanding work on behalf of the American people" in a statement, noting her work coordinating responses to natural disasters like the Joplin tornado and Hurricane Sandy.
"Since day one, Janet has led my administration’s effort to secure our borders, deploying a historic number of resources, while also taking steps to make our immigration system fairer and more consistent with our values," Obama said. "And the American people are safer and more secure thanks to Janet’s leadership in protecting our homeland against terrorist attacks."
Confirming a new DHS secretary could prove a particular challenge for the White House because of the role the department could play in implementing the new immigration reform package.
Under the Senate bill passed late last month, the DHS would be charged with implementing the E-Verify program requiring employers to verify the status of workers, as well as new border security measures Republicans see as essential to the immigration effort.
It's also possible that Senate Republicans could hold up a nomination in protest of the Obama administration's decision last year to suspend the deportation of certain illegal immigrants who entered the country as children.
"Well, that'll be fun. A new DHS Secretary in the middle of the immigration debate," Brendan Buck, a spokesman for House Speaker John Boehner (R-Ohio), tweeted Friday.
Sen. Jeff Sessions (R-Ala.) said Napolitano’s tenure was "defined by a consistent disrespect for the rule of law" that has caused the morale of immigration offiicers to plummet.
"Any selection — interim or permanent — to replace Secretary Napolitano must disavow these aggressive non-enforcement directives or there is very little hope for successful immigration reform," Sessions said in a statement.
House Homeland Security Chairman Mike McCaul (R-Texas) said that Napolitano's "departure is a substantial addition to the growing list of unfilled key leadership positions within the Department, and the Administration should move swiftly to fill the gaping holes in its management."
Christian Beckner, the Deputy Director of the Homeland Security Policy Institute at the George Washington University, noted in a blog post Friday that there are now 15 senior-level vacancies at DHS, including the deputy secretary, under secretary for intelligence and analysis, commissioner of Customs and Border Protection, and the director of Immigration and Customs Enforcement.
Conservatives began targeting Napolitano early in her tenure after the release of a DHS memo examining right-wing extremism.
The document, made public in 2009, suggested that the election of the first African American president, Democratic pushes for gun control, and the economic downturn — among other factors — could inspire growth of right-wing extremism.
The report also suggested that extremist groups would attempt to recruit and radicalize military personnel returning from the wars in the Middle East, earning broad condemnation from veterans groups.
Napolitano also came under fire for telling CNN in 2009 that "the system worked" during the attempted bombing of Northwest Airlines Flight 253 on Christmas Day.
Umar Farouk Abdulmutallab, a 23-year-old Nigerian al Qaeda operative, was unable to detonate the plastic explosive sewn into his underwear. Napolitano later clarified for her comments in an interview with NBC News, arguing her remark had been taken out of context and that no one "is happy or satisfied with" that the bombing very nearly occurred.
That attempted attack, in concert with other terrorist targeting of commercial airliners, led DHS to implement more invasive screening processes at the nation's airports — leading to protest from some Americans who objected to screening machines that could see through clothes and more aggressive pat-downs.
“I knew I’d actually made it when I had my own name in the Drudge Report. You know, that’s the standard," Napolitano said at a December 2011 event at the Council of Foreign Relations.
In announcing their decision, the leader of the search committee that picked Napolitano said the was the right person to lead the state's flagship university.
“While some may consider her to be an unconventional choice, Secretary Napolitano is without a doubt the right person at the right time to lead this incredible university," Sherry Lansing, the UC regent who led the search committee, said in a statement obtained by The Los Angeles Times.
"She will bring fresh eyes and a new sensibility -- not only to UC, but to all of California. She will stand as a vigorous advocate for faculty, students and staff at a time when great changes in our state, and across the globe, are presenting as many opportunities as challenges.”
More recently, Napolitano was criticized by Republican lawmakers after revelations about suspected Boston Marathon bomber Tamerlan Tsarnaev.
Tsarnaev's travel to Russia in 2012 — during which some have speculated he was radicalized — went unnoticed by a travel screening system because of a typo. Because of the misspelling, the FBI — who had be warned by Russian authorities that Tsarnaev could be linked to terror groups — was unaware of his travel.
Napolitano was also the target of a July 2012 lawsuit alleging gender discrimination against male staffers at the Department of Homeland Security.
This story was last updated at 11:47 a.m.