WASHINGTON — In their quest to reduce former Vice President Joe Biden’s early polling lead in the 2020 Democratic presidential race, some of his rivals risk undercutting their prime focus of removing President Donald Trump from office.

First New Jersey Sen. Cory Booker and then California Sen. Kamala Harris jumped on Biden over long-past racial issues, while recognizing his stature as a bona fide civil rights champion. Each has questioned Biden’s past willingness to work with old Southern segregationists in the Senate on other matters, and Harris has slammed him for past opposition to school busing to promote racial integration in his home state of Delaware.

Biden, first stunned by the attacks from these two prominent black legislators from his own party, defended himself last week in a long CNN interview with Chris Cuomo. Biden argued that he remains a “center-left” progressive in the ideological spat within the party despite efforts to paint him as a moderate whose time has passed.

Perhaps suffering most in this latest outlook is Vermont Sen, Bernie Sanders. He clings to his self-identification as a Democratic socialist while being attacked from the left by fellow Democrats seeking a share of the same ideological turf, and he’s slipping in the polls.

In all this, the party whose first 2020 objective is said to be deposing Trump risks pivoting to internal squabbling that can undermine that goal. Biden continues to insist he is the best and strongest Democrat to get that job done. A recent Washington Post poll found that 45 percent of Democrats still see him as having the best chance to defeat Trump. Only 18 percent rated Sanders’ prospects highest, and just 8 percent gave the nod to Harris.

In the CNN interview, Biden also resisted efforts to pin him down on selection of a female running mate if he is nominated next year. He diplomatically observed that he would favor a woman for president or vice president if he doesn’t make it to the Oval Office himself.

Biden explicitly included Harris despite her calculated effort to cut him down to size with her earlier debate assault on him over busing. As a former vice president, however, Biden established a strong personal and working relationship with his president that endured over eight years. Clearly he would want to replicate that compatibility in his own presidency.

As the 2020 election approaches, Biden has three very strong and politically experienced women running against him who would be well-placed to be his running mate if they survive the campaign in his good graces.

One of the females rising in the presidential sweepstakes, Massachusetts Sen. Elizabeth Warren, also has had issue differences with Biden in the past, including over his past defense of his home-state credit-card industry.

Warren also has been a supporter of Sanders’ Medicare for All proposal, which would replace private-industry coverage. Biden argues for building on the Affordable Care Act and retaining the private coverage that now protects millions whose premiums are paid by employers or labor unions and who want to keep it.

Harris, in a show of hands at that first Democratic debate, raised hers to kill private coverage, but then said she had misunderstood the question and would back it as a public option to provide additional insurance. She will not be immune from questions about this and other aspects of her own record and consistency.

A third female presidential candidate, Sen. Amy Klobuchar of Minnesota, would also be available to Biden as a running mate, and she shares the same moderate Democratic ideological ground. Klobuchar has never lost an election in her state, a particular Biden target in his oft-claimed identification as Mr. Working Class from coal-country Scranton, Pa.

But such political musings come much too early in the election cycle to be taken as definitive. If the Democrats’ most critical goal is to drive Trump from power more than a year from now, they will be wise to minimize all side issues that can cause division among them. That would include where the party goes after the election, if indeed it can show Trump the exit door.

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 juleswitcovercomcast.net.

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