WASHINGTON — President Trump came under withering attack on Thursday from some of his strongest supporters, who were outraged and unforgiving about his decision to set aside, for now, a fight over building the border wall he has long promised as part of a deal with Democrats on legislation to protect young, undocumented immigrants.

The tentative arrangement, which the president hashed out over dinner on Wednesday night at the White House with the top-ranking congressional Democrats, Senator Chuck Schumer of New York and Representative Nancy Pelosi of California, set off accusations of betrayal and renewed nagging doubts about whether Mr. Trump was in jeopardy of alienating some of his most ardent backers on the right.

No promise was more central to his campaign than building the border wall. And no constituency was more passionate in defending Mr. Trump’s pledge than the conservatives who believed he would be uncompromising in his approach toward illegal immigration.

The condemnation was swift and came from many different conservative corners: members of his own party in Congress, his most steadfast boosters on talk radio and the grass roots.