
Immigration was dead simple when Joseph R. Biden Jr. was campaigning for president: It was an easy way to attack Donald J. Trump as a racist, and it helped to rally Democrats with the promise of a more humane border policy.
Nothing worked better than Mr. Trump’s “big, beautiful wall” that he was building along the southern border. Its existence was as much a metaphor for the polarization inside America as it was a largely ineffective barrier against foreigners fleeing to the United States from Central America.
“There will not be,” Mr. Biden proclaimed as he campaigned against Mr. Trump in the summer of 2020, “another foot of wall constructed.”