Trump on Sunday morning announced via tweet that he’d be tapping Mark Morgan, who served as the chief of U.S. Border Patrol under Obama, to head Immigration and Customs Enforcement (ICE). Morgan must be formally nominated by the president and confirmed by the Senate.

“I am pleased to inform all of those that believe in a strong, fair and sound Immigration Policy that Mark Morgan will be joining the Trump Administration as the head of our hard working men and women of ICE,” Trump wrote. “Mark is a true believer and American Patriot.” The Washington Post reports that senior ICE leaders were taken by surprise, only learning of the selection from the tweet.

Morgan is a former career FBI agent who served as the Border Patrol chief for the last six months of the Obama presidency, but was then replaced when Trump assumed office. Since then, Morgan has spoken to various media outlets backing many of Trump’s immigration proposals, such as building the border wall and sending migrants to sanctuary cities. “I was removed. I’m standing up and saying, ‘I should have disdain for them, but I don’t because they are right,” he said in a January interview with Law and Crime. Morgan has consistently characterized current immigration trends as an unprecedented crisis.

Trump withdrew the nomination of Ronald Vitiello, who had 30 years of experience with the Border Patrol, to head ICE in April. The Post reported at the time that White House adviser Stephen Miller had been lobbying against Vitiello. The president said of the move, “We’re going in a tougher direction. We want to go in a tougher direction.” Former Homeland Security secretary Kirstjen Nielsen resigned two days later.

“Here’s phase one of what ‘tougher’ looks like, in my opinion,” Morgan told the Los Angeles Times last month when news broke of Vitiello’s nixed nomination, “They have to stop expecting that Congress is going to do their job. DHS is going to have to address this issue all alone.” Morgan claimed that there is an incentive for undocumented immigrants to “grab kid, step one foot onto U.S. soil” to bypass border laws. He further said that, while he doesn’t believe that the White House will reimpose its family separation policy, it must take dramatic action “even if we lose in the courts.”

The Trump administration has been ramping up efforts to tighten border security in recent weeks. The Justice Department directed judges late last month to deny bond hearings for asylum seekers, which would leave them in detention for months while they wait for their claims to be adjudicated. The administration is also asking Congress for additional border security funding to expand detention space and enact other measures.