A year ago, Democrats were tantalized by the prospect of fielding the most diverse array of presidential candidates ever. Among the upward of two dozen people running for their 2020 nomination were African Americans, Asian Americans, a Latino, a half-dozen women and a married gay man.

Who would have predicted that, as the race rounds the bend into Super Tuesday, the party’s choices would come down to three white guys, whose ages range all the way from 77 to 78? Now they are trying to figure out which of that trio from the Silent Generation has the best chance of beating another septuagenarian, President Trump, in November.

On Saturday, African Americans in South Carolina reconfigured the race by throwing a lifeline to former vice president Joe Biden, the onetime front-runner who had stumbled in Iowa, New Hampshire and Nevada.

“We are very much alive,” Biden jubilantly declared during his victory speech. And for the first time in a while, he sounded that way.

Black voters accounted for nearly six in 10 of those who cast ballots in the South Carolina Democratic primary. Preliminary exit polls indicated they favored Biden over Sen. Bernie Sanders (I-Vt.), the leader in the national race, by 4 to 1. Biden also benefited from the fact that more than two-thirds of South Carolina voters were 45 and older, another group he won handily.

His blowout victory in South Carolina will no doubt give Biden a bounce, and perhaps restore some sheen to the premise of electability that he lost in the first three contests.

Within minutes of the polls closing Saturday night, Biden picked up the endorsement of former Virginia governor Terry McAuliffe, whose state is one of the ones voting on Tuesday. “I think he has the best shot of beating Donald Trump and, most importantly, not only winning the presidency but helping us in Senate and House races,” McAuliffe said.

What remains to be seen is how far this revival of Biden’s momentum can carry him, given how little money he has and how thin his organization is across the map.

The next round of contests will effectively be a national primary that includes delegate-rich California, where polls have Sanders leading the rest of the field by 2 to 1. Most critical of the things to watch Tuesday will be how well Biden’s limping campaign fares when it comes up against the massive spending that Mike Bloomberg, the billionaire former mayor of New York, has been putting on the national airwaves for months.

Another factor is the presence of a handful of other candidates — among them, Sens. Elizabeth Warren (Mass.) and Amy Klobuchar (Minn.) and former South Bend, Ind., mayor Pete Buttigieg — who are still in the race and splintering off shares of the vote.

Unless Biden or Bloomberg can quickly consolidate the support of moderate Democrats, Sanders will continue racking up pluralities in the primaries to come, allowing him to move further and further ahead in the competition for convention delegates. That prospect has touched off a panic among the party establishment, which fears that having a self-identified democratic socialist at the top of the ticket would not only cost Democrats the White House but potentially their majority in the House.

Though the Democratic field is rapidly losing its diversity, in South Carolina at least, Biden looked like the kind of candidate who could build the broad-based coalition that the party knows it needs to win in November.

There was a new edge in Biden’s speech on Saturday night, one that revealed how he is positioning himself for what has become a three-man race for the nomination.

The former vice president alluded to the anxiety that many Democrats feel about Sanders: “We have the option of winning big or losing big — that is the choice.”

Biden also put in a double-barreled dig at Sanders, who is not a Democrat, and Bloomberg, a former Republican: “If Democrats want a nominee who’s a Democrat — a lifelong Democrat, a proud Democrat, an Obama-Biden Democrat — then join us,” he said.

With polls opening in the Super Tuesday states a little more than 48 hours after they closed in South Carolina, Saturday night offered Biden little chance to savor an achievement for which he has waited a very long time. This is his third run for the White House. His victory in South Carolina — resounding as it was — marked the first primary he had ever won.

“For all those of you who’ve been knocked down, counted out, left behind, this is your campaign,” Biden said.

Within a few weeks, we will know whether what we have just seen in South Carolina is the beginning of one of the most remarkable comeback stories in recent political history or just another bend in a presidential race that may still have many twists to come.

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