Markwayne Mullin officially assumed the post of Department of Homeland Security secretary on Tuesday afternoon.

Attorney General Pam Bondi swore Mullin in during an Oval Office ceremony as President Donald Trump looked on.

“It’s a great day for me, because I have a lot of confidence in this gentleman,” Trump said ahead of the swearing-in. “We’re thrilled to swear in our new secretary of Homeland Security, great American patriot, to put it mildly, Markwayne Mullin.”

Trump lauded Mullin’s work at the Capitol, where he served as a congressman before becoming a United States senator, a post he held before becoming the DHS chief.

“He was there in Congress as a member of the House and then as an outstanding United States Senator, and he really has been outstanding,” Trump said.

“He has been a close and vital partner in helping us secure the border, stop migrant crime, end the scourge of illegal drugs, and make America safe again and make America great again,” the president added.

Mullin said he was “the most nervous” he has ever been during the swearing-in.

“It just seems surreal being in the Oval Office and having the president of the United States speak so highly of me and then recognize my family and know my family by name. It’s humbling, and I never take it for granted,” he said.

“I made this very clear that I don’t care what color your state is. I don’t care if you’re red or you’re blue,” he added. “At the end of the day, my job is to be secretary of homeland and to protect everybody the same. And we will do that. I’ll fight every single day.”

Mullin added that no one will “outwork” him, which the president enjoyed and referenced Mullin’s wrestling background.

“I love that expression, ‘No one’s going to outwork me.’ That’s a wrestler’s expression, isn’t it? That’s a good wrestler’s expression,” he said.

Mullin replaces former DHS Secretary Kristi Noem after being confirmed by the Senate in a 54-45 vote Monday night.