He said the Senate still had an obligation to pass legislation to strengthen the country’s border, even if doing so would give Mr. Biden a political win. That does not appear to be the position most of his colleagues are taking.
Senator Christopher S. Murphy, the Connecticut Democrat who has been playing a lead role in the negotiations, said Mr. Trump’s opposition to the deal should come as no surprise.
“That is the cold, hard reality of Donald Trump, who just sees the border as a political issue, not as a policy problem to solve,” Mr. Murphy said.
Some hard-right Senate Republicans who are deeply opposed to the emerging deal accused Mr. McConnell of trying to pin its demise on Mr. Trump. Senator Ron Johnson, Republican of Wisconsin, said Mr. McConnell was “trying to shift blame to President Trump for what I would say are his failed negotiations.”
Senator J.D. Vance, Republican of Ohio, said it was shortsighted to send a “weak sauce” border security bill to the House, where Speaker Johnson has suggested it would be dead on arrival. That strategy Mr. Vance said, “allows the president to blame ‘MAGA’ Republicans for the failure of a border security package when it reality, what failed was a very weak border security package that didn’t actually do anything.”
Karoun Demirjian and Carl Hulse contributed reporting.