What just happened? The Democratic presidential nomination race, which gave signs of lasting months, is now basically over.

Sen. Bernie Sanders won North Dakota and lost Washington after carrying a lead on Wednesday. In Michigan and Missouri, where he won 50% and 49%, respectively, against Hillary Clinton in 2016, he carried 36% and 35% against former Vice President Joe Biden in Tuesday's primaries. He was wiped out even worse in Mississippi and lost in Idaho.

It turns out that the apparent similarity between the Republican contest in 2016 and Democrats' contest in 2020 was only apparent. Bernie Sanders is not Donald Trump; former Mayor Pete Buttigieg and Sen. Amy Klobuchar weren't Sens. Ted Cruz and Marco Rubio; and Joe Biden turned out not to be former Gov. Jeb Bush.

Different candidates' motivations and perceptions were different. Looking back, Rubio and Cruz seemed to genuinely believe they were destined to win, the Republican first Hispanic president following the Democratic first black president. So Rubio stayed in the race through Florida in mid-March and Cruz through Indiana in early May. Former Gov. John Kasich stayed in even later as the Republican candidate for those who can't stand Republicans.

Buttigieg and Klobuchar got out after the first four contests. Mayor Pete left because his utter rejection by black voters left him unviable in a party hooked on identity politics, whose claims to moral superiority rest on its support from almost all black voters. Hence its reflex to call Republicans -- not just Donald Trump but also Mitt Romney -- racists.

Minnesota's Klobuchar left after failing to get liftoff in neighboring Iowa and getting 4% and 3% in Nevada and South Carolina. Her gender was no help: Democrats had already chosen their first woman nominee. The ire of feminists was reserved for the rejection of Elizabeth "I have a plan for that" Warren, even though she fizzled in national, Iowa and New Hampshire polling in November, four months ago, when her "Medicare for All" plan imploded.

Similarly, identity politics theory failed to operate as Democrats seemed nonplussed by the prospect of a second black nominee after the election of the first black president. Sen. Kamala Harris, Sen. Cory Booker and the all-but-invisible former Gov. Deval Patrick failed to attract appreciable support from black (or non-black) voters.

As for Sanders, his support among rural and small-town voters has consistently lagged behind 2016 levels. That was glaringly evident in Michigan, where he carried 73 of 83 counties against Hillary Clinton and lost every one, even university counties, to Joe Biden. He lost all 114 Missouri counties and all 82 of Mississippi's.

Sanders' strength outside major metropolitan areas in spring 2016 has been considered an augury of Trump's success there that November. But maybe it was also predominantly a gauge of Clinton's weakness in "deplorables" country. That raises the question of whether Trump can replicate his big general election margins there this year.

In any case, it seems clear that the world's oldest political party, which, since its formation in 1832, has been a coalition of out-groups, of people who are not considered typical Americans but often form a national majority together, is determined to nominate a 77-year-old white European-descended male.

Biden is also one who, in the words of veteran Fox News analyst Brit Hume, "like so many people his age, is losing his memory and is getting senile." Hume, seven months younger than Biden, admits, "I have traces of this myself," and distinguishes Biden's recent lapses from his long-term propensity for gaffes, which are "kind of harmless."

One Biden characteristic is his adherence to conventional wisdom, or at least to a Democratic version of conventional wisdom, which is usually taken as common sense by the press, over a long career -- long enough to where, on many issues, conventional wisdom has moved on, leaving Biden vulnerable to current fashions. His 1970s opposition to school busing and 1990s support of tough-on-crime legislation were both criticized by primary opponents but may not be problems now.

His opposition in 1991 to the brief and successful Gulf War and his support in 2003 of the much longer and more stressful Iraq conflict now look more problematic. But the press is not inclined, and Donald Trump may be too maladroit, to argue, as former Defense Secretary Robert Gates did, that Biden has "been wrong on nearly every major foreign policy and national security issue over the past four decades." Biden's strengths and weaknesses leave him a candidate with no easily predictable electoral consequences.

In the meantime, the coronavirus threat and how President Donald Trump responds to it will steal attention from the Democrats, also with no easily predictable electoral consequences.