Thursday night's presidential debate showcases Democratic diversity: three women, two African-Americans, a Latino and an Asian-American, candidates ranging from age 37 to 78.
But one notable category won't be represented under debate qualification guidelines. Not a single governor made the cut.
That reflects a sharp turn in the American path to the White House, which until recently ran so often through state capitals. But ideological polarization and discontent with government has so devalued gubernatorial currency that 2020 almost certainly will become the third presidential contest in the last four without a governor as either the Democratic or Republican nominee.
"I seriously doubt I will ever see a major party nominee who was or is a governor" again, said Justin Sayfie, a Florida Republican activist. He experienced the wrong end of that shift in 2016 when his former boss, ex-Gov. Jeb Bush, lost the GOP nomination to President Donald Trump.
In the 10 presidential elections between 1976 and 2012, one or both parties nominated a governor in nine. Governors — Jimmy Carter, Ronald Reagan, Bill Clinton and George W. Bush — won seven of those races.
The outcomes followed a familiar logic. A governor's executive responsibilities provided the closest facsimile to the presidency itself. In state houses, as in the White House, landmark achievements required the ability to command bipartisan support.
But the logic breaks down when frustrated voters disdain government and those associated with it. And the widening ideological divide between Democrats and Republicans turns bipartisan cooperation increasingly into a fantasy.
Presidential candidates "aren't running on established, moderate records," observes political scientist Thad Kousser, co-author of the 2012 book "The Power of Governors." "They're running on extreme positions."
At times, Kousser adds, successful governorships and presidential campaigns have come to appear mutually exclusive. Party activists and donors look upon bipartisan compromise as a "curse," while stronger ideological stances generate backlash at home and make governors less effective.
The 2008 contest pitting Sen. Barack Obama against Sen. John McCain was the first presidential race in three decades without a governor on either party's ticket. Four years later, Republicans nominated Mitt Romney despite concerns about his Massachusetts gubernatorial record that included a state-level forerunner to Obamacare.
With no government experience at all, Trump bested Bush and eight other state executives for the 2016 Republican nomination. In addition to Sen. Bernie Sanders, ex-Secretary of State Hillary Clinton beat former Govs. Martin O'Malley of Maryland and Lincoln Chafee of Rhode Island.
The 2020 race appears no friendlier to governors. Trump's dominance of his party renders the two former governors challenging him — Mark Sanford of South Carolina and William Weld of Massachusetts — nuisance candidates.
None of the three governors who entered the Democratic race has demonstrated significant appeal. Two — Jay Inslee of Washington and John Hickenlooper of Colorado — have already dropped out.
The third, Steve Bullock of Montana, failed to qualify for Thursday night's debate on the basis of polling support and number of individual contributors. His chances of overtaking the leaders — former Vice President Joe Biden and liberal Sens. Bernie Sanders and Elizabeth Warren — appear bleak.
The debate stage will not lack executive experience altogether. But three Democrats with mayoral experience — Pete Buttigieg of South Bend, Indiana, Cory Booker of Newark, and Julian Castro of San Antonio — also face uphill climbs.
The small number of cases makes declaring presidential trends risky. A change in public sentiment, or one especially charismatic governor, could shift the path to the White House back again.
But the digital revolution in disseminating information and raising campaign funds makes that a challenge. Republican activist Sayfie said the internet overlays its own form of artificial intelligence on political choices, to the detriment of the last generation's formula.
"Outsiders to the governing establishment are disproportionately rewarded over insiders," Sayfie said. "Governors, by definition, are insiders."
"The internet's political AI penalizes any candidate who has ever reached political compromise," he concludes. "Those two penalties alone make it nearly impossible for governors to be chosen to receive the nomination of their party for president."
Correction: An earlier version misstated the status of Pete Buttigieg. He is currently mayor of South Bend.