Carter’s nomination now in the hands of Republicans on Capitol Hill.
President Obama officially announced Ashton Carter to be his nominee for Defense secretary Friday.
Carter served in the No. 2 job at the Pentagon as deputy Defense secretary between 2011 and 2013. He was a top official at DOD during the first five years of Obama's presidency.
"I relied on his expertise, and I relied on his judgment," Obama said at the announcement at the White House.
Carter was unanimously confirmed by the Senate then and has broad support among top defense-minded Republicans on Capitol Hill. If the Senate approves him for the job, Carter will be the fourth official to run the Pentagon during the Obama administration.
Obama made it clear that one of the most critical issues Carter will tackle will be managing the defense budget.
"We are going to have to squeeze everything we have out of the resources we have in order to be as effective as possible," Obama said.
In his new role, Carter will not only have to deal with geopolitical threats and a tight budget, he will also have to repair damaged political relationships between top leaders at the Pentagon and the White House, as well as corral congressional leaders on Capitol Hill.
Carter said he took the job because of the "seriousness of the strategic threats" the U.S. faces, but also because of the "of the deep respect and abiding love" he had for the men and women in uniform.
While the White House has been criticized for micromanaging the Pentagon, Carter said he had no intention of holding back his opinions on the job.
"If confirmed in this job I pledge to you, my most candid, strategic advice," Carter said.
During the announcement, Obama said that Carter has always fought to get troops the equipment they needed during their service. Obama praised Carter's attention to even the smallest details, such as visiting wounded soldiers and traveling to war zones for holidays, often on his own time and with little fanfare.
Unlike current Defense Secretary Chuck Hagel or political celebrities such as former CIA Director Leon Panetta, who had national name recognition, Carter is better known as working behind the scenes at the Pentagon.
Hagel will stay on the job until Carter can be confirmed by the Senate. That process is expected to take several weeks at the very least.
Hagel, who resigned from his post amid reports of tensions between himself and the White House, did not attend Carter's announcement.