President Donald Trump announced Friday that the Department of Homeland Security (DHS) Secretary John F. Kelly will be taking over as the White house chief of staff after Reince Preibus’ ouster, which has left the top position at the DHS vacant.

According to the leadership structure at the DHS, in the absence of the secretary the deputy secretary takes over, effectively making Elaine Duke the new acting Secretary of Homeland Security. The DHS announced Friday that Kelly will remain secretary till July 31, after which Duke is scheduled to take over.

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Trump announced Kelly's new position Friday when he tweeted: "I am pleased to inform you that I have just named General/Secretary John F Kelly as White House Chief of Staff. He is a Great American, and a Great Leader. John has also done a spectacular job at Homeland Security. He has been a true star of my Administration." The president also thanked Preibus for his services to the country in a separate tweet.

A Senate confirmation will be required to permanently fill Kelly's position. Kelly released a statement on his departure from the DHS on Friday evening, thanking "the tremendous men and women of DHS."

"I thank you for the opportunity to serve as your Secretary. When I left the Marines, I never thought I would find as committed, as professional, as patriotic a group of individuals," Kelly said in his statement. "I was wrong. You accomplish great things everyday defending our nation and I know your exceptional work will continue."

Duke was sworn in as the deputy secretary of Homeland Security in April this year after her Senate confirmation by a vote of 85-14.

"I am grateful to have this opportunity to further mature the Department and continue improving its efficiency and effectiveness," Duke said at her confirmation hearing for the deputy position in April.

"If confirmed, I promise to lead DHS in enforcing the law with respect and integrity. I will be honest in my assessments and recommendations, and relentless in pursuing excellence. Such commitments are critical at this juncture in homeland security," she added, according to CNN.

While serving as the deputy secretary, Duke led "all efforts related to the strategic execution of DHS’s vital missions," including a push for the increase in security measures in carrying large electronics in airplanes traveling to the country, according to her DHS biography.

She has served in the federal government for almost 30 years and spent the past eight years working with DHS, where she served as the undersecretary for management from 2008 to 2010. Before being sworn in as the deputy secretary at DHS, Duke worked as the principal of Elaine Duke & Associates, LLC, where she "provided acquisition and business consulting services to large and small businesses," as described in her bio.

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Before working with the DHS she also served at the Department of Defense. She completed her graduation degree in business from New Hampshire College and then received her MBA from Chaminade University of Honolulu. According to CNN, during her stint at DHS, she also worked in management, in acquisition at the Transportation Security Administration and also as chief procurement officer.

During her public service career, Duke has been honored with several accolades including the the DHS Secretary's Medal, Presidential Meritorious Rank Award, the Coast Guard's Distinguished Public Service Medal, the TSA Silver Medal for Customer Service, and the Department of the Army Commander's Award for Public Service.