WASHINGTON — President Donald Trump said Thursday that Republican Sen. Markwayne Mullin will replace Kristi Noem as Department of Homeland Security secretary.

Mullin will take over as secretary on March 31. 

"The current Secretary, Kristi Noem, who has served us well, and has had numerous and spectacular results (especially on the Border!), will be moving to be Special Envoy for The Shield of the Americas, our new Security Initiative in the Western Hemisphere we are announcing on Saturday in Doral, Florida," Trump said on Truth Social.

Noem is the first Cabinet secretary to leave during Trump’s second term, ending a tumultuous tenure overseeing immigration enforcement, including Operation Catahoula Crunch in Louisiana. Noem also oversaw the department during the high-profile killings of Alex Pretti and Renee Good in Minnesota.

According to the New York Times, Louisiana Sen. John Kennedy told reporters on Thursday that he received a call from the president about Noem's testimony to the House.

“Put it this way,” he said. “His recollection and her recollection are different.”

Rep. Troy Carter, a Democrat, said in a statement that the removal of Noem reflects calls for accountability from the administration.

“Today’s decision underscores an important truth. Even when Democrats do not control the votes in Congress, accountability can still prevail when the three pillars of our democracy work together: Congress, the courts and the community," Noem said.

Mullin, who represents Oklahoma, has served for three years in the Senate and previously served for a decade as a congressman.

"As the only Native American in the Senate, Markwayne is a fantastic advocate for our incredible Tribal Communities. Markwayne will work tirelessly to Keep our Border Secure, Stop Migrant Crime, Murderers, and other Criminals from illegally entering our Country, End the Scourge of Illegal Drugs and, MAKE AMERICA SAFE AGAIN," Trump added. "Markwayne will make a spectacular Secretary of Homeland Security."

Carter added that he feels Mullin's nomination will not end "the need for vigilance."

"Senator Mullin has publicly applauded many of the very practices under Secretary Noem that raised serious concerns across the country. His appointment does not erase those concerns. Congress will be watching closely, and we will not hesitate to hold this new leadership accountable if those same harmful practices continue," Carter said.