With Speaker McCarthy deep in his debt ceiling negotiations with President Biden, a new threat of federal default is emerging from left-wing Democrats in the Senate. The noble comrades, including Senators Warren and Sanders, are warning that they would refuse to accept any debt ceiling deal that includes the House GOP’s trims to federal welfare programs or a rollback on Mr. Biden’s war on fossil fuels.

This obstructionism marks a contrast with Mr. Biden’s new assurance that “We will not default. Every leader has said that.” No so fast, say the leftist legislators. “We cannot reach a budget agreement that increases the suffering of millions of Americans who are already living in desperation,” they warn in a letter. Instead, they urge Mr. Biden “to exercise your authority under the 14th Amendment,” a constitutional dead end.

What a change of tune for Ms. Warren, who in March was complaining that the House GOP sought “to use the debt ceiling to hold our government and our economy hostage.” She warned “how dangerous it would be to default on the national debt” and what a “disaster.” It was wrong to use the debt ceiling for “leverage” on policy matters, she said. Now, it seems, Ms. Warren and her leftist coterie are preferring default to compromise.

Ms. Warren is joined by Senator Merkley of Oregon, who is seeking to bolster Mr. Biden’s confidence that “he will have support on Capitol Hill if he decides to use the 14th Amendment” to borrow money on his own authority. The alternative, Mr. Merkley warns, would be to accept GOP budget trims and agree to “unleash fossil fuels on America.” He contends “both of those are absolutely unacceptable.”

The senatorial hysterics reflect a belated awareness of the failure so far of Mr. Biden’s negotiating strategy with the House GOP. Even the New York Times’ Paul Krugman now says that Mr. Biden “blew it” by refusing to accept the political reality of a Republican House majority. As early as November, Mr. Krugman says that without budgetary concessions “it was obvious” that the GOP plan would rely on “refusing to raise the federal debt limit.” 

Mr. Biden “needed a strategy to head off the looming crisis,” Mr. Krugman observes. “More and more, however, it looks as if there never was a strategy beyond wishful thinking.” No wonder Ms. Warren and her political politburo are now so distraught. They think that the 14th allows Mr. Biden to borrow money on his own authority. Even Treasury Secretary Yellen appears to see the folly of this idea, warning of a “constitutional crisis.”

Just to mark this point: It is to only the Congress that the Constitution, in Article I, Section 8, grants the power to “borrow money on the credit of the United States.” Plus, too, it is only against an appropriation passed by Congress that any money of any kind from any source — taxes or borrowing or created by the Fed  — can be “drawn from the treasury.” So no presidential borrowing could be spent without passing the GOP-led House. 

Of the 14th Amendment scheme, Mr. Biden worries “it would have to be litigated.” Hence his turn to negotiations. Senator Schatz avers that Hill Democrats are “not going to swallow” any concessions to the House GOP. Ms. Warren calls a work requirement proposal advanced by Republicans “despicable” and, with Senator Fetterman, vows to vote against any deal that contains it. So she might get the default she suddenly covets.