WASHINGTON - The US Senate on Monday confirmed Senator Markwayne Mullin's nomination for Department of Homeland Security (DHS) secretary, replacing embattled Kristi Noem, amid the department's continued shutdown.

The upper chamber voted 54-45 to approve 48-year-old Mullin, who has served in the Senate since 2023, following a decade in the House representing the state of Oklahoma. One Republican senator voted against the nomination and two Democrats supported it.

Mullin's nomination, announced by President Donald Trump on March 5, came amid growing bipartisan frustration with Noem's leadership and marked the first Cabinet shakeup of Trump's second term.

Noem has been under bipartisan pressure after federal law enforcement officers fatally shot two US citizens in Minneapolis in January and further angered Trump with her performance at congressional hearings early this month, when senators from both parties grilled her on a 200 million-dollar ad campaign project, among other issues.

The fatal shootings of two US citizens -- Renee Good and Alex Pretti -- by federal enforcement in Minneapolis in January have prompted Democrats to seek changes to how immigration agencies operate.

Disagreement over immigration enforcement regulations led to a deadlock in Congress, as Democrats requested that funding for DHS be removed from an omnibus funding package, resulting in a brief partial shutdown from Jan 31 to Feb 3.

The Congress then passed a funding package, which funded multiple US federal agencies for the remainder of the fiscal year, but DHS only received a two-week continuing resolution at current funding levels, allowing both parties and the White House to continue negotiations.

Over the past few weeks, negotiations between the two parties on immigration enforcement have shown little progress.

The Senate rejected the DHS funding bill for the fifth time on Friday, leaving the department's operations, including the Transportation Security Administration, the Coast Guard, and the Federal Emergency Management Agency, crippled.