With the full order of finish still in doubt, Mr. Buttigieg used his caucus-night speech to deliver a stern warning about the implications of nominating Mr. Sanders, urging Democrats not to “rush” into anointing him as their candidate. In his most pointed critique to date, Mr. Buttigieg said Mr. Sanders’s agenda lacked broad support and asserted that the senator did not give “a damn” about the swing-state Democrats in Congress who are scared of running with him on the same ticket.
“Senator Sanders believes in an inflexible, ideological revolution that leaves out most Democrats, not to mention most Americans,” Mr. Buttigieg said, adding that Mr. Sanders wanted to “reorder the economy in ways most Democrats, not to mention most Americans, don’t support.”
Mr. Biden appeared at a Las Vegas union hall while most votes were still uncounted to claim a comeback and vowed victory in South Carolina. “Y’all did it for me,” he told supporters, trying out a new line aimed at his rivals. “I ain’t a socialist, I ain’t a plutocrat, I’m a Democrat.”
Mr. Biden’s campaign asserted that he would finish in second place here, a claim challenged by Mr. Buttigieg’s aides.
The apparent scale of Mr. Sanders’s victory margin presented an immediate challenge to the rest of the candidates, many of whom have been counting on a drawn-out nomination fight to give them time to catch up. But time is plainly running short, and few of Mr. Sanders’s rivals have a clear path to closing his advantage. Among them, only Mr. Biden has a realistic chance of winning South Carolina next week, the sole remaining contest before Super Tuesday on March 3.
That may leave the other Nevada runners-up scrambling to accumulate delegates but with few opportunities to win whole states. Several candidates who were counting on a wave of national momentum coming out of the early states showed no sign of achieving that: Ms. Klobuchar, who claimed a third-place finish in New Hampshire as a major breakthrough, appeared to be near the back of the pack in Nevada. Mr. Buttigieg, who nearly deadlocked Mr. Sanders in Iowa and New Hampshire, did not come close to him on Saturday.
Should Mr. Biden prevail in South Carolina — an outcome that is no longer seen as a near-certainty — there could be enormous pressure on the other moderates in the race to stand down and give him a clean shot at Mr. Sanders.