President Trump’s supporters, up to and including Trump himself, have tried to delegitimize Robert Mueller’s necessary investigation for crassly partisan purposes. But it’s also true that Trump’s opponents, eagerly taking reports of each new crumb of circumstantial corroboration as ironclad proof of collusion, are rapidly delegitimizing the presidency, our government and democratic processes.

In their haste to brand Trump a tool, they’re unwittingly doing the Russians’ work for them: validating the notion that our democracy is a sham.

While Russia clearly preferred Trump to Hillary Clinton, so far no one has produced conclusive evidence showing that the Trump campaign colluded with the Russian government.

Yet Rep. Adam Schiff (D-Calif.), the ranking Democrat on the House Intelligence Committee and by now a cable-news fixture, insists there is “ample evidence in the public domain on the issue of collusion,” though he’s never cited anything of the sort. Rep. Ted Lieu (D-Calif.) suggests that a “cloud of treason” hangs over the Trump administration. Former CIA Director John Brennan insinuated that Russia is blackmailing the president, a grave accusation, of which he later conceded, “I do not know if the Russians have something on Donald Trump.”

Meanwhile, film director Rob Reiner has recruited former intel chiefs James Clapper and Leon Panetta to sit on the advisory board of his “Committee to Investigate Russia,” which might be necessary were the FBI, House, Senate and Mueller not already doing just that.

To be sure, Trump’s public posture toward Russia is unduly solicitous. But his policies are a different matter. On Monday, however, as part of a coordinated response with our most important allies, the US expelled 60 Russian diplomats and ordered the Russian consulate in Seattle closed. After calling NATO “obsolete” in 2016, Trump’s Defense Department in 2017 proposed a boost in financial support for the alliance; he’s announced the sale of antitank weapons to Ukraine; and, according to reports, US military forces recently killed “at least 100” Russian mercenaries in Syria.

Yet so attached to the collusion narrative are some Trump critics that their theories are impervious to countervailing data. When Trump announced former UN ambassador John Bolton as his next national security adviser and video emerged of Bolton speaking to a Russian gun-rights group, Sen. Tim Kaine (D-Va.) tweeted: “Can John Bolton even get a security clearance? Ties to Russian allies of Vladimir Putin?”

Considering Bolton’s long, consistent record as a foreign-policy hawk on everything, including Russia, the charge is at best paranoid, at worst dishonest.

Of Trump, Democratic National Committee Chairman Tom Perez declared in a speech last year, “You didn’t win this election.” No doubt thanks, at least in part, to incessant conspiracy theorizing, 57 percent of young Americans viewed Trump as illegitimate in March 2017. Mueller’s investigation has yet to conclude, but 70 percent of Democrats already support impeachment.

Trump critics have seized upon Mueller’s indictment of 13 suspects from the Internet Research Agency, a Kremlin-backed outfit charged with waging the 2016 disinformation campaign, as the exegesis of Russia’s decisive role in winning the election for Trump.

While Moscow’s dirty tactics should be exposed and countered, the notion that Twitter bots and ersatz Facebook posts swung an American presidential race in which more than 135 million ballots were cast and more than $2 billion was spent — and the current hysteria over data firm Cambridge Analytica’s lifting of Facebook user information — demonstrates a remarkable lack of faith in the decision-making capacities of the American public.

Mueller should be given time to complete his investigation, and both sides should be prepared to accept findings that diverge from their assumptions.

In the meantime, we would all do well to keep in mind what the intelligence community determined to be Russia’s primary objective: “undermine faith in the US democratic process.”

By insisting, in the absence of conclusive evidence, that the president is not legitimate, that his administration is acting on behalf of a foreign adversary and that the election itself was determined by Russian interference, Trump’s critics are doing just as much to “undermine public faith in the US democratic process” as wild-eyed Republicans rambling about a sinister “deep state.”

James Kirchick is a visiting fellow at the Brookings Institution.

Special to The Washington Post