With the 2016 presidential primaries finally over, Bernie Sanders seems to be clinging to his surprisingly strong, if losing, campaign for the Democratic nomination essentially to keep his “revolution” within the party going.

He says he can “do the arithmetic” that indicates he has the slimmest of chances of convincing superdelegates declared for Hillary Clinton to switch to him at the party's convention in Philadelphia late next month. But he apparently hopes he can extract certain platform and policy commitments with what in poker would be a very small pair.

The fact is that some of his objectives should be easily conceded by the presumptive nominee, including agreeing to a flat $15-an-hour federal minimum wage. But his drive for a Canadian-type single-payer health care system run by a federal bureaucracy clearly is a bridge too far for Ms. Clinton to cross. She committed to strengthen and improve Obamacare, not submit it to a disruptive reconsideration by Congress.

Mr. Sanders, as a declared democratic socialist, obviously wants to use the impressive army of supporters he mobilized in the primaries to move the Democratic Party further to the left, particularly over the issue of income inequality that was a centerpiece of his campaign. But Ms. Clinton is already aboard that train, if favoring a lighter push on the throttle than Mr. Sanders in his talk of revolutionary changes.

Their differences would matter more if the current presidential race had not become such an obvious matter of national security, with the prospect of an irrational and temperamentally unstable Republican nominee vying for the Oval Office. As Mr. Sanders has already said, he will do anything to ensure that Donald Trump does not win the November general election.

Mr. Trump by both word and demeanor has established that he has neither the temperament nor stability required for running this country. The desperate if ineffective pushback within his own captured party echoes that view among many establishment Republicans.

But the level of dissatisfaction and anger in the electorate this year has enabled Mr. Trump to sell his verbal concoction of racial and ethnic division, misogyny, personal insult and self-promotion to a scary mass of voters. Consequently, the possibility that he will be elected cannot be denigrated or laughed off.

That threat in the end is the paramount reason Bernie Sanders must now subordinate his lofty ambitions of social revolution to the ominous peril at home and in foreign policy represented by the Trump candidacy.

Mr. Trump is struggling now in the wake of his latest self-inflicted political wounds. First he ascribed ethnic bias to the federal judge presiding over a California civil case alleging fraud by the defunct Trump University. Then, in the wake of the mass shooting in Orlando, Fla., he tried to take cover with boastful remarks about foreseeing the attack, and even implying some mysterious collusion by President Barack Obama.

It must be recognized that Mr. Trump's campaign is being fueled to a great degree by voter discontent that often borders on substantial hatred of rival Hillary Clinton. Polls now indicate, however, that Ms. Clinton is benefiting from Mr. Trump's latest outbursts.

The time has come for Bernie Sanders to put the well-being of the Democratic Party, and of the whole country, ahead of his revolution and rally his progressive constituency to Ms. Clinton's campaign. He may have to bite his tongue about his primary season assault on her as a willing tool of Wall Street and the “1 percent” of society he says preys on the American middle and poorer classes.

The overarching threat of Donald Trump also requires now that Mr. Sanders put aside his vision of a more socially conscious America and devote his remarkable energy to help assure that America doesn't stumble into the hands of a demonstrably unqualified and dangerous demagogue. In the process, he may also be throwing a life preserver to the Grand Old Party, which is flirting with extinction by virtue of the bizarre Trump candidacy.

Jules Witcover is a syndicated columnist and former longtime writer for The Baltimore Sun. His latest book is “The American Vice Presidency: From Irrelevance to Power” (Smithsonian Books). His email is juleswitcover@comcast.net.