New Delhi, March 24 -- The Senate on Monday confirmed President Donald Trump's nomination of Senator Markwayne Mullin to lead the Department of Homeland Security, installing a close ally of the president at a critical juncture for US immigration enforcement and national security policy.

Mullin, a 48-year-old Republican from Oklahoma, secured confirmation in a 54-45 vote, with near-unanimous Republican backing and support from two Democrats. His appointment follows a contentious confirmation hearing and comes amid heightened scrutiny of the department's public standing and operational challenges.

The new secretary replaces Kristi Noem, whose tenure was marked by bipartisan criticism over leadership decisions and the use of taxpayer funds...