"I know you will fulfill your duties with dedication, determination and resolve".
In accepting the nomination, Nielsen said she hopes to "live up to the standards the American people expect and deserve".
If confirmed by the Senate, Nielsen will lead an agency charged with securing the nation's borders and airports, enforcing immigration laws, coordinating disaster relief efforts and overseeing the Secret Service and Coast Guard.
Nielsen, who now serves a Chief of Staff John Kelly's deputy, will likely be approved by the upper chamber.
She was also a senior fellow at George Washington University's Center for Cyber & Homeland Security. Among the other candidates considered, according to people familiar with the process, was Representative Michael McCaul, Republican of Texas and the chairman of the House Homeland Security Committee. "I am eager to hear from Ms. Nielsen on what her main priorities are for the Department and its 230,000 employees".
Added Frances Townsend, her boss at the White House during the Bush administration: "She is tough as nails, competent and has rightly earned the president's respect".
One former Bush administration official expressed concern over her selection, describing Nielsen as less qualified than Elaine Duke, who is now leading the department in an acting capacity.
Neilsen is an expert in homeland and national security policy.
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