Democrats can complain that their presidential race has come down to a 77 year-old white man, Joe Biden, against a 78 year-old white man, Bernie Sanders. But that is what has happened. Now, after the departure of Michael Bloomberg Wednesday morning, what is needed is for the last remaining also-ran -- Elizabeth Warren -- to quit the race. A simple, clarified Biden-Bernie contest is the only way to settle the fundamental conflict that has plagued Democrats through the last two presidential nominating cycles.

Democrats once crowed about having the "most diverse field" in presidential history. There were African Americans — Kamala Harris and Cory Booker; women — Harris, Warren, Amy Klobuchar, Kirsten Gillibrand, Tulsi Gabbard; Latino — Julian Castro; gay — Pete Buttigieg; white men — Beto O'Rourke, Tim Ryan, Bill de Blasio; and elderly white men — Biden, Sanders, and, later, Bloomberg.

Now, it is down to Biden and Sanders. The party's rush to Biden on Super Tuesday was so swift it almost invites rethinking in the days to come. In short: Will there be a Biden hangover?

Yes, Biden was the front-runner in the national Democratic race from the moment he declared until early February; Democratic voters are familiar with his name atop the leader board. But because of the peculiar circumstances of 2019, Biden has not been subjected to the withering, extended scrutiny that being a presidential front-runner can bring. During the impeachment of President Trump, some press accounts seemed to spend more time defending Biden against Republican attacks than delving into his positions or his long public life.

Then, when Biden crashed after terrible performances in Iowa, New Hampshire, and Nevada, the scrutiny machine shut off. That was certainly not a surprise; the political world mostly left Biden for dead. The attention of many Democrats and the press turned to Sanders, the new front-runner. The senator from Vermont took a pretty good beating for much of February.

Then came South Carolina. Biden, with the support of black Democrats, made a huge comeback. Then, in 72 hours, came a frenzied dash back to the former front-runner. Buttigieg and Klobuchar quit and endorsed Biden. Voters made nervous by nonstop attacks on Sanders took another look. Exit polls showed late deciders broke overwhelmingly for Biden. The result was a truly super Super Tuesday for Biden — wins in Texas, Virginia, North Carolina, Minnesota, Massachusetts, Alabama, Arkansas, Oklahoma, and Tennessee.

The sense of a Biden blowout was enhanced by the fact that most of his wins took place in the eastern and central time zones, where polls closed first. The early hours of television coverage of Super Tuesday appeared much of the time to be one Biden win after another.

Sanders won his home state of Vermont, plus Colorado and Utah. Had he won Texas and California, what appeared to be an early Biden runaway would have ended up pretty even. But Biden, again, on the strength of those late-deciders, took Texas. It appears Sanders is headed toward victory in California, a win that will keep him in the delegate race. But there is no doubt Sanders fell short on Super Tuesday.

Elizabeth Warren won nothing. Michael Bloomberg won American Samoa. Now that Bloomberg is out, Warren will face increasing pressure to get out. Meanwhile Biden, with virtually no campaign apparatus in Super Tuesday states, much less in those still to come, will face a new world. Sanders is still out there. It's time for a one-on-one.

What is at stake is the resolution of a deep divide in the Democratic Party between Sanders' young, revolution-minded constituency, now strengthened by significant numbers of Hispanic voters, and Biden's older, more cautious electorate. The outcome might be decided less on the substance of issues than on the temperament and stamina of two men who, were either elected, would turn 80 shortly after entering the White House. Many Democrats, especially those who were proud of their candidates' diversity, will wonder how they got here.

