WASHINGTON (AP) — President Donald Trump said Tuesday he will nominate acting Secretary of Homeland Security Chad Wolf to the top spot in the agency, rewarding a forceful advocate for administration policy whose leadership has been challenged on legal grounds.

The president made the announcement on Twitter, praising Wolf's management of an agency that plays a major role in the key Trump administration policy areas of immigration and crime at the expense according to critics of its core mission of protecting the nation from external threats.

"I am pleased to inform the American Public that Acting Secretary Chad Wolf will be nominated to be the Secretary of Homeland Security," Trump tweeted. "Chad has done an outstanding job and we greatly appreciate his service!"

Wolf's prospects for Senate confirmation are unclear. There is a narrow window for Wolf to be confirmed before the Nov. 3 election, with the Senate away until Labor Day and then scheduled to recess in mid-October.

He's likely to face criticism over the role of DHS in carrying out administration efforts to limit both legal and illegal immigration and the deployment of federal agents in tactical gear to confront protesters this summer in Portland, Oregon, without the agreement of state and local authorities.

"I think given his past actions, he's an awful choice," Sen. Chuck Schumer, the Senate's top Democrat, said in a call with reporters.

Wolf's position of acting secretary has already been the subject of legal challenges. He has been in what is supposed to be a temporary role for over 500 days, more than twice as long as permitted under the federal law intended to limit how long someone can hold a position in the government without Senate confirmation.

Wolf was named acting secretary in November 2019 following Trump's removal of his predecessor, acting Secretary Kevin McAleenan, after six months in the post leading an agency that has the third largest budget in the federal government.

The Government Accountability Office said in a finding released Aug. 14 that the federal rules of succession had been violated at DHS and neither Wolf nor deputy acting Secretary Ken Cuccinelli could legally hold their positions without Senate confirmation.

That gave new legal ammunition to the many legal challenges to the Trump administration's restrictive immigration policies. The administration disputed the GAO finding and insisted that both men could legally hold their positions under a different federal statute, the Homeland Security Act.

Homeland Security, which was created in response to the Sept. 11, 2001, terrorist attacks, has more than 240,000 employees. It includes U.S. Customs and Border Protection as well as the agency that processes applications for citizenship and work visas. It also manages disaster relief, counterterrorism, election security, and the Coast Guard.

Wolf has defended the administration decision to use DHS to protect federal property and monuments following the protests that erupted around the nation this spring over the police killing of George Floyd in Minneapolis. That included the deployment of federal agents to Portland, where they clashed repeatedly with protesters.

He earlier served as chief of staff when Kirstjen Nielsen ran the department, when a "zero tolerance" policy on illegal immigration at the southern border resulted in the separation of thousands of parents, mostly from Central America, from their children.

"I am honored to be nominated by President Trump to lead the men and women of the Department of Homeland Security in safeguarding the American people," he said in a statement after the president announced his nomination to be secretary. "As the Homeland faces evolving threats from natural disasters, violent opportunists, malign cyber actors, and transnational criminal organizations, the mission of DHS is as critical as ever."