Mullin promises to earn Dem votes as GOP colleagues pounce on his seat

President Donald Trump's move to fire Homeland Security Secretary Kristi Noem and tap Sen. Markwayne Mullin, R-Okla., as her replacement triggered a domino effect in Congress.

Before Mullin can take the helm of the Department of Homeland Security (DHS), he has to be confirmed. And once confirmed, someone will have to take his seat. Both caveats come with their own hurdles.

Senate Democrats may try to toss a wrench into the confirmation process and extract promises for reforms to the agency, particularly Immigration and Customs Enforcement (ICE). DHS has been closed for three weeks, and the shutdown will likely continue for at least a month.

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Senate Minority Leader Chuck Schumer, D-N.Y., has vowed to oppose Mullin and argued that changes need to be made regardless of who runs the agency.

"It’s a question of policy, not personnel," Schumer said. "The Senate should not consider any DHS secretary nominee until DHS and ICE are reined in."

Mullin has staunchly opposed Democrats’ demands to reopen the agency and whether he’ll budge to get their votes remains to be seen.

But he’s open to speaking with Schumer and his caucus and wants to earn their votes. Whether he can do that before Trump’s March 31 deadline is up in the air.

"The Department of Homeland Security is to keep everybody — regardless of whether you support me, if you don't support me, regardless of what your thoughts are — I'm here to enforce the policies that Congress passed," Mullin said.

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Then there’s the race for succession. Mullin, who is currently near the end of his first term in the upper chamber, was in the midst of running for re-election. With his appointment by Trump, that seat is now wide open for Republicans hungry to reach the Senate.

Oklahoma Gov. Kevin Stitt, a Republican, will choose who fills Mullin’s Senate seat in the short term. But it’ll be up to voters in the Sooner State to pick their next senator.

"I will be looking to appoint a strong, small-government conservative voice to support President Trump and protect Oklahomans’ way of life," Stitt said on X.

And GOP hopefuls have already begun crowding the potential primary race for his seat within hours of Trump’s announcement.

Reps. Stephanie Bice, R-Okla., and Kevin Hern, R-Okla., are already showing interest, Fox News Digital was told.

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A source close to Bice told Fox News Digital that she was considering running for the likely open Senate seat first, which Bice followed with her own public statement on Thursday evening.

"President Trump has made an excellent choice. Markwayne is a great friend and a fierce advocate for the America First Agenda. I’m excited for him to take the helm at DHS," she posted on X. "It’s the honor of a lifetime to stand side by side with President Trump for the people of Oklahoma. I’ve received encouragement from every corner of this great state to run for the U.S. Senate. And it’s something I’m carefully considering."

Meanwhile, Fox News Digital was told that Hern — who currently serves in House leadership in the role of GOP Policy Committee chairman — already began calling players within the Republican orbit to get their support.

Multiple people familiar with Hern’s thinking told Fox News Digital that he intends to run.

Hern is also generating buzz among Senate Republicans. Sens. Jim Banks, R-Ind., Bill Hagerty, R-Tenn., and Ron Johnson, R-Wis., have all come out in support of him.

Neither Hern nor Bice is interested in being appointed by Stitt, however, likely due to Oklahoma’s unusual laws dictating how Senate vacancies must be filled.

A mid-term vacancy is traditionally filled by the state’s governor, after which an election occurs at the next pre-scheduled race date. The governor’s appointee must sign an affidavit swearing they will not run in that election.

In this case, Mullin was up for re-election in November, so anyone seeking the office will have to run in a June primary and then be up for a full six-year term at the end of this year.

But that also means that Bice and Hern will both be able to run for Mullin’s current seat without risking the House GOP’s own razor-thin majority.