By Ted Hesson and Steve Holland

WASHINGTON (Reuters) – U.S. President Joe Biden on Tuesday will order a review of asylum processing at the U.S.-Mexico border and the immigration system as he seeks to undo some of former President Donald Trump’s hardline policies, two senior administration officials said.

Biden will also create a task force to reunite migrant families who were separated at the U.S.-Mexico border by Trump’s 2018 “zero tolerance” border strategy, the officials said on a call with reporters on Monday.

Immigration advocates have urged the new Democratic administration to move quickly but officials say they need time to unravel the many layers of immigration restrictions introduced during the Trump era and to put in place new, more migrant-friendly systems.

“Fully remedying the actions will take time and require a full-governance approach,” one of the officials said.

Biden’s executive orders on Tuesday will not address repealing a coronavirus-era order, known as “Title 42,” that was issued under the Trump administration and allows border officials to expel almost all people caught crossing the border illegally.

He will also mandate a review of the Migrant Protection Protocols (MPP), a program that pushed 65,000 asylum seekers back to Mexico to wait for U.S. court hearings. Most returned to their home countries but some remained in a makeshift camp near the Mexican border.

The Biden administration has already stopped adding people to the program but crucially it has not yet outlined how it will process the claims of those already enrolled.

“I can’t tell you exactly how long it will take to put in an alternative to that policy,” another official told reporters on Monday in response to a reporter’s question about processing people enrolled in the program.

Chad Wolf, former acting U.S. Department of Homeland Security secretary under Trump, said in an interview that halting the MPP program was a mistake because it had been an effective deterrent to illegal immigration.

“If you do have a surge (of migrants), you’re taking one of your tools off the table,” he said in reference to the program.

Biden advisers have said in recent months they will not immediately roll back Trump’s restrictive border and asylum policies due to concerns about encouraging illegal immigration during the coronavirus pandemic. Biden himself said in December that his administration needed to set up “guardrails” so that the United States does not “end up with two million people on our border.”

Biden’s actions on Tuesday will follow six immigration orders he issued on his first day in office and will further jumpstart his ambitious pro-immigrant agenda that seeks to erase Trump’s restrictive policies on legal and illegal immigration.

HURDLES

But Biden’s efforts face logistical challenges and opposition from Republicans, according to immigration policy experts, former officials and activists on both sides of the issue.

Lawsuits by conservative groups could potentially slow down Biden’s agenda. A federal judge last week temporarily blocked one of his first immigration moves – a 100-day pause on many deportations – after the Republican-led state of Texas sought an injunction.

Trump won the presidency in 2016 while making border security a major theme of his campaign. If Biden fails to prevent surges in illegal immigration at the U.S.-Mexico border, he could give ammunition to Republicans in the 2022 congressional elections, said Sarah Pierce, a policy analyst with the Washington-based Migration Policy Institute.

“This is the thing that rallied Donald Trump supporters,” she said.

Biden’s review of Trump’s so-called “public charge” rule is expected to start the process to rescind it, according to two people familiar with the plan. The rule makes it harder for immigrants who are poor or need government help to secure residency and stay in the country.

Biden’s expected order setting up the task force to reunite parents and children separated at the southern border was a key election promise.

The task force, however, will face a daunting challenge in trying to track down the parents of more than 600 children who remain separated, according to a January court filing in a related case. The children are living with relatives or in foster care, according to an attorney representing plaintiffs in the litigation.

The task force will be led by Alejandro Mayorkas, one of the senior officials said on Monday. Mayorkas, Biden’s nominee to lead the Department of Homeland Security, is expected to face a Senate confirmation vote on Tuesday.

(Reporting by Ted Hesson and Steve Holland in Washington; Editing by Ross Colvin, Aurora Ellis and Alistair Bell)