By virtue of the separate decisions of Donald Trump and Joe Biden to cast the approaching 2020 campaign as a bitter showdown between them, it already is reducing the large field of Democratic candidates to a premature sideshow.
When Messrs. Trump and Biden went to Iowa last Tuesday and exchanged barbs from separate locations, the other 22 Democratic hopefuls in the race could only shrug and continue to plod on in their lonely efforts to horn in on what so far has been the Trump vs. Biden main event.
Mr. Biden's strategy to cast next year's presidential campaign as a two-man race, with himself as the strongest Democrat to beat Mr. Trump, has been handed a major boost from Mr. Trump, in alleging that the former vice president is the foe he most wants to face, and the weakest one at that.
As the two worked the Iowa battleground at a safe distance from each other, most headlines and television reports reinforced the image of a two-man competition. It was fortified by the decisions of the other declared Democratic combatants to focus on policy differences among each other, in quest of being seen as the most progressive in a party moving leftward.
For the time being, their practical opponent of choice has not been Mr. Trump or Mr. Biden but Sen. Bernie Sanders of Vermont, the 2016 darling of progressives, in the hope of wresting that mantle from him. Meanwhile, Mr. Biden insists he is the most progressive, while clinging to his old reputation as a standard party liberal of the old school.
Thus, as all the other Democratic contenders vie for the right to replace Mr. Biden against Mr. Trump, the frontrunner only has his stature reinforced by Mr. Trump's eagerness to apply his customary bullying against him, calling him "a loser," "the weakest mentally" and "a dummy."
Meanwhile Mr. Biden, who launched his campaign by tying Mr. Trump to the white supremacists at the Charlottesville protest, almost by default is being portrayed in the news media as the point man now standing between Mr. Trump and the destruction of Americans' most cherished democratic values.
The best approaching opportunity to do something about it will be at one of two debates later this month, to which 20 of the Democrats have been invited by the Democratic National Committee to compete on national television. Mr. Biden is included to take part in one of them.
At one stop in Iowa the other day, he appeared to minimize the debates as a game-changer, observing that "this is going to be an appearance less than a debate." While, at age 76, Mr. Biden is criticized as over the hill, he is a veteran debater whose skills Barack Obama once cited as a reason he chose him as his running mate in 2008.
But Mr. Trump went out of his way the other day to demean Mr. Biden by saying Mr. Obama "took him off the trash heap." Then he added: "He's a different guy. ... He looks different than he used to." So said the president who is only three years younger than Mr. Biden.
In any event, there is plenty of time and opportunity for the other 22 Democrats in the competition for the 2020 nomination to break through. The first convention delegate-selection caucuses in Iowa don't start until February and many state primaries thereafter.
Mr. Biden's decision to take on Mr. Trump from the outset, however, has served him well, even as the other Democrats in the race have begun to go on the offensive against the former vice president, resurrecting old allegations of plagiarism and new ones of inappropriate behavior toward women.
So far they have not appeared to do much damage to Mr. Biden in the polls as the Democratic frontrunner. But his absence from early campaign events, including a recent California party convention show-and-tell, have raised complaints that he is playing it safe.
Unlike many or most of the 2020 Democratic wannabees, Joe Biden is a known political commodity after 36 years of public service as a U.S. senator and eight as president-in-waiting under Obama. What voters have seen is what they get now, for better or for worse.
Jules Witcover's latest book is "The American Vice Presidency: From Irrelevance to Power," published by Smithsonian Books. You can respond to this column at email@example.com.