Washington DC - The Senate on Monday confirmed President Donald Trump's ally, Markwayne Mullin, as the new chief of the Department of Homeland Security.

Senators voted 54-45 for 48-year-old Republican Mullin, a former wrestler and martial arts fighter who previously served as a senator for Oklahoma.

Mullin replaces Kristi Noem as DHS head, after she was fired earlier this month in part for her handling of a massive deployment to Minnesota, during which federal immigration agents shot dead two US citizens.

At his confirmation hearing before the Senate last week, Mullin said one of his goals would be to steer DHS and its widely-reviled ICE agency away from the spotlight.

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Democratic Senator Dick Durbin of Illinois expressed skepticism of Mullin's promises, saying in a statement: "While the problems at DHS are larger than any one person, I remain concerned that Senator Mullin will not rein in ICE abuses."

"I voted no, because I will not vote to install another yes-man to enable Donald Trump's worst instincts."

Mullin, who also faced opposition from fellow Republicans, had signaled openness to requiring judicial warrants for immigration enforcement operations, a potential shift from current policy and a key demand from Democrats in ongoing funding negotiations.

DHS funding has been lapsed since February 14, as Democratic lawmakers seek to implement reforms to immigration enforcement.

The month-long DHS shutdown has impacted other services overseen by the department, including the Transportation Security Administration.

TSA staff around the country have worked for weeks without pay, with more than 300 quitting since the start of the shutdown, leading to extended travel delays as airports struggle to screen air travelers.

Trump announced ICE agents would be deployed to airports impacted by the travel delays, which caused chaos and confrontations on Monday.