WASHINGTON — The Senate on Monday confirmed Markwayne Mullin as the new Secretary of Homeland Security, succeeding Kristi Noem. This decision came after a heated confirmation hearing last week, where Senator Rand Paul (R-Ky.) expressed concerns about Mullin’s temperament, accusing him of being too combative for the position.

The confirmation saw Mullin, a Republican senator from Oklahoma, approved with a 54-45 vote. He is set to lead the Department of Homeland Security, currently facing challenges and criticism over the president’s “mass deportations” policy, which has negatively impacted public opinion during the president’s second year in office.

There has been criticism from within the Republican ranks regarding the tactics employed by Immigration and Customs Enforcement, as well as Kristi Noem’s controversial rhetoric and her use of over $220 million in taxpayer money for an ad campaign featuring herself.

Only two Democrats, Senators John Fetterman of Pennsylvania and Martin Heinrich of New Mexico, voted in favor of Mullin, joining 52 Republicans. Senator Rand Paul stood as the only Republican to vote against Mullin’s confirmation.

Mullin, a newcomer to the Senate in 2023 after replacing the retiring Senator Jim Inhofe, will now oversee a workforce of more than 250,000 federal law enforcement officers. The department has faced a 37-day shutdown stemming from Democratic opposition.

“The swift confirmation of Senator Mullin underscores the significance placed on him by the Senate, the administration, and the mission that President Trump has emphasized in his 2024 campaign,” a Republican aide shared with The Post.

A former mixed martial arts fighter, Mullin is known for fostering some of his most collegial relationships through a bipartisan, bicameral workout group that meets every morning on Capitol Hill. His boundless energy often has him in the halls of the Senate bouncing a pink rubber ball, a keepsake from middle school that he’s dubbed his “pacifier.”

“I hope whoever is assigned to his security detail is ready to keep up,” Senate Majority Leader John Thune (R-SD) said in a floor speech Monday before the vote.

Mullin’s warm personal feelings for his family and fellow lawmakers was also on display during his confirmation fight, during which he fought back tears sharing how Trump personally cared for his teenage son — and footed the bill for treatments — when he was struck with a traumatic brain injury.

But Paul clashed with him in a March 18 Senate Homeland Security Committee hearing, denouncing him as “a man with anger issues” who had “no regrets” about threatening to brawl with Teamsters President Sean O’Brien three years earlier — or about calling the chairman a “freaking snake” who apparently deserved to have six of his ribs cracked by a crazed neighbor in a 2017 altercation at home in Bowling Green, Ky.

Though he mocked Mullin for supporting the modern-day equivalent of “dueling,” Paul himself had warned journalists reporting on instances of alleged plagiarism in one of his own published books back in 2017: “Like I say, if dueling were legal in Kentucky — if they keep it up — it’ll be a duel challenge.”

Sen. Gary Peters (D-Mich.), the top Democrat on the panel, also rejected Mullin for lacking “the experience or the temperament” to lead the domestic law enforcement agency and for not being “forthright and transparent” about a 2016 “classified” trip abroad he took while serving in the House.

But Mullin’s warm working relationships with Republicans and Democrats — as well as O’Brien, whom he now considers a “good friend” — helped secure Sen. John Fetterman’s support to clear the committee and others to eventually be confirmed on the Senate floor.

Sen. Martin Heinrich (D-NM) said in a statement Sunday before the vote that he has a “constructive working relationship” with Mullin and looked forward to discussing issues critical to his border state with someone besides Trump’s previous DHS chiefs.

“We need a leader at DHS. We must reopen DHS,” added Fetterman (D-Pa.). “My AYE is rooted in a strong committed, constructive working relationship with Senator Mullin for our nation’s security.”

Most Senate Democrats opposed Mullin’s appointment as they are seeking reforms within DHS — including changes to the process to obtain warrants for arrests and banning masks for agents — after the fatal shootings of two Americans by federal immigration agents in Minnesota earlier this year.

“We will not enter a home or a place of business without a judicial warrant, unless we’re pursuing the individual that runs into a place of business or a house,” the DHS nom said in his confirmation hearing, signaling a possible compromise on a heated issue.

Trump’s border czar Tom Homan downplayed the prospect of shifts in DHS enforcement when speaking with reporters outside the White House on Monday, while noting the lowering of tensions since the withdrawal of federal agents from Minneapolis last month who were part of Operation Metro Surge.

“We’re already looking at deployment of cameras nationwide; we’re already looking at strategic approach and targeting operations and prioritization of criminals and national security threats,” Homan said.

“What I’m explaining to them is a lot of these changes are already taking place, not changes in law but the way we execute the mission.”

The border czar added: “I want the government back up, but we’re not going to put ICE officers at further risk. We’re not going to take tools away from them that help them arrest more criminals and national security threats.”

Homan has huddled in closed-door meetings with GOP and Democratic negotiators on various proposals — including a pitch Trump rejected on Sunday to separate ICE from other DHS funding.

White House staff and Sen. John Kennedy (R-La.) had supported funding ICE through a forthcoming budget reconciliation bill.

Thune had offered the fix to the president over the weekend without success, according to sources with knowledge of the talks.

Trump refused to back the compromise and challenged Democrats to instead vote for the SAVE America Act, a bill that would require voters to provide proof of citizenship when registering and identification when casting a ballot.