Donald Trump said on Sunday that Mark Morgan, who was border patrol chief under former president Barack Obama, will head the US Immigration and Customs Enforcement agency.

“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 on Twitter.

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. Mark is a true believer and American Patriot. He will do a great job! — Donald J. Trump (@realDonaldTrump) May 5, 2019

The position is a key role in an administration seeking to crack down on migrants crossing the US-Mexico border, according to people familiar with the matter.

Morgan, led the Border Patrol in the final months of the Obama administration and was forced out from the position after Trump assumed the presidency in early 2017. Morgan, a former FBI agent, supported a border wall, one of Trump’s signature 2016 election campaign issues.

At the time it was reported that Morgan told senior border patrol agents about his ousting during a brief video conference, saying he was asked to leave and that he decided to resign rather than fight the request, according to unnamed official who was on the call.

But now he’s been brought back into the fold.

Morgan is not optimistic Congress currently has the ability to fix immigration policy – or even wants to deal with it, and has “shown again and again their failure to do what’s right”, he told Fox News last week.

In a toughened stance, he said the legislative body should focus on “fixing” the so-called Flores Settlement, which prevents migrant families and children caught crossing the border unlawfully from being detained for more than 20 days.

He said Congress also needs to amend the Trafficking Victims Protections Reauthorization Act, which prevents unaccompanied illegal immigrants under the age of 18 from being returned home to Central America when caught.

“If they would do those two legislative fixes they would end ‘catch-and-release’ and 85% of the humanitarian crisis would end immediately and the numbers would stem,” Morgan said.

Trump’s former acting director of Ice, Ronald Vitiello, quit last month after the president told reporters that he was pulling his nomination for the Ice director’s job because he wanted to go in a “different direction” with someone “tougher”.

Trump has strongly indicated that he would make the issues of illegal immigration and border security a centerpiece of his 2020 election campaign. Apprehensions at the southern border have surged despite his administration’s stricter immigration policies, and earlier this month he pushed out Homeland Security Secretary Kirstjen Nielsen and other top immigration officials.

Trump has ordered his administration to propose regulations that would impose fees on migrants applying for asylum and speed up the application process. In a presidential memorandum released on Monday night, Trump said “the security and humanitarian crisis” at the US-Mexico border “undermines our nation’s security and sovereignty”.

Meanwhile, the Trump administration has revised training guidelines for asylum officers in ways that could make it harder for migrants seeking refuge in the United States to pass an initial screening, Reuters has reported.

The revisions to a lesson plan used by hundreds of asylum officers suggest the government is finding new ways to narrow who can access asylum as bolder policy proposals with that same goal have been blocked by federals courts, former government officials and immigration experts who reviewed the internal plan told the news agency. The changes could potentially lead to more denials and deportations before migrants’ full cases can be heard, they said.