THE PORTION of Americans who favor more immigration stands at the highest level since Gallup began asking the question more than a half-century ago. Nearly 8 in 10 believe immigrants are good for the country. Those views, along with the central role immigrants have played in the United States’ economic success and global standing, buttressed President-elect Joe Biden’s pro-immigration platform.

If he is to implement it, Mr. Biden will also need a single-minded focus on overhauling immigration policy. Which is to say, Mr. Biden must emulate President Trump.

It is broadly true that incompetence has been a hallmark of the Trump White House, yet immigration policy has been a notable exception. The administration has adeptly dismantled decades of immigration policy and norms and, under the relentless tutelage of White House senior adviser Stephen Miller, managed to slash legal migration levels by about half compared with 2016. The administration gutted refugee and asylum admissions; halved the entrance of immediate relatives of current U.S. citizens; and, under cover of the coronavirus pandemic, completely halted the so-called diversity migration program, which grants green cards to underrepresented migrant populations, many from Africa.

To reverse course, as he has pledged to do, Mr. Biden would be wise to appoint his own immigration wizard. He made a good start by announcing he will nominate Alejandro Mayorkas, an immigrant himself and a top official in the Obama administration’s Department of Homeland Security, to lead that department. Mr. Mayorkas has referred to “dreamers,” the young undocumented migrants raised in this country after their parents brought them here as children, as “part of the tapestry of American life” — not exactly the sort of pronouncement one heard from the Trump administration.

Restoring a sane and compassionate immigration system will be largely, though not wholly, within reach of Mr. Biden’s executive powers. He can increase refugee admissions relatively quickly, although it will take time to build back to pre-Trump levels. He can immediately stop work on Mr. Trump’s wasteful wall at the southern border, now funded by cannibalizing dozens of U.S. military programs. He can ensure the renewal of work permits and end the threat of deportation for dreamers, and grant reprieves to hundreds of thousands of migrants whose temporary protected status Mr. Trump tried to remove — even though many have lived here for more than a decade.

It will take longer to undo the hundreds of rule changes the Trump administration used to neuter legal immigration programs, including one that disqualifies green card applicants deemed likely ever to need government benefits. As for a pathway to citizenship for more than 10 million unauthorized immigrants, that will require legislation — a daunting prospect as long as Republicans control the Senate.

The politically trickiest part of Mr. Biden’s agenda may be rebuilding the asylum system, which the Trump administration has dismembered under the slander of “catch and release.” No doubt, the country needs a functional process whereby migrants fleeing persecution at home can legally seek asylum here. It will be Mr. Biden’s challenge to rebuild such a system without establishing a magnet for new waves of illegal immigration.

Mr. Biden promised to reverse course on immigration, and he won a comfortable majority in the process. That gives him a mandate to return this country to a posture that is welcoming, not hostile, to those who would contribute to its vibrancy.

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