Mullin, a Republican senator from Oklahoma known for his close friendship with Trump, has tried to present himself as a steady hand, saying his goal as secretary would be to get the department off the front page of the news.
Senators confirmed him on a largely party-line vote, 54-45.
Routine funding for the Department of Homeland Security has lapsed since Feb. 14, leading to long waits at U.S. airports as Transportation Security Administration agents call out rather than work without pay.
MMA fighter takes on Homeland Security
While the senator comes to the position after more than a dozen years in Congress, and with the management experience of running an expanding family plumbing business in Oklahoma, he has not been seen as a key force in immigration issues.
A former mixed martial arts fighter and collegiate wrestler who has led early-morning workout sessions in the members-only House gym, he became close with members of both parties and is often seen as a negotiator in partisan Washington.
It is his loyalty to Trump that landed him the job, and he’s not expected to sway from the president’s approach. Mullin was a strong supporter of Trump's immigration agenda and ICE officers before being tapped for the DHS job.
“I can have different opinions with everybody in this room, but as secretary of homeland I’ll be protecting everybody,” Mullin said during his confirmation hearing.
Immigration enforcement at center of funding stalemate
Mullin’s first challenge will be to restore routine funding to the department that has been blocked since mid-February as Democrats demand tighter restraints. They want immigration officers to identify themselves and not wear masks; refrain from enforcement operations around schools, churches, hospitals and other sensitive locations; wear body cameras; and obtain a judge's approval on warrants before entering people's homes or private spaces.
At his confirmation hearing last week, Mullin sought to portray himself as a steady hand at a pivotal time for the agency.
Democratic Sens. John Fetterman of Pennsylvania and Martin Heinrich of New Mexico joined the other Republicans in voting to confirm the nominee.
“Markwayne Mullin is ready to lead," said Sen. John Barrasso of Wyoming, the No. 2 ranking Republican. He said Mullin will “serve with seriousness and character. He will be a leader who makes our country safer.”
