After two years of looking forward to the moment the report of special counsel Robert Mueller would be released, the conclusion of his probe was a bitter disappointment for President Trump’s partisan critics. Democrats’ confidence that Mueller would make the bad dream of 2016 go away vanished the instant they learned he had found no evidence of the collusion with Russia they were sure would sink Trump.

They were just as unhappy that the letter from Attorney General William Barr closed the door to a prosecution of Trump for allegedly obstructing justice in the case.

But rather than accepting defeat and moving on to the business of attacking Trump on the issues, Democrats can’t give up on the conspiracy theories they’ve been peddling since Hillary Clinton’s defeat. Far too much effort and emotion has gone into the business of treating Trump as an illegitimate occupant of the White House to change tactics now.

The investigations being pursued by Democratic-controlled House committees offer friendly venues for further pursuits of Trump. But shorn of the incendiary Russia charge that some Democrats likened to treason, even those who vowed to impeach Trump understand that probing his inaugural committee or private business dealings falls flat as a “resistance” rallying point.

Yet if the thesis that Trump plotted with Moscow is now irrevocably debunked, how to continue to stoke their base’s conviction about the president’s illegitimacy?

Had they not spent the last two years lionizing Mueller, they might have been able to pivot quickly and assert that the report was itself a coverup. But that option was foreclosed by Trump’s vitriolic attacks on Mueller that elevated him to the status of a national hero for those who despise the president.

That left liberal talking heads and pundits as well as Democratic members of Congress with only one available target: Attorney General William Barr.

Barr is coming under fire for essentially clearing the president on the charge of obstruction of justice even though his letter to Congress about the Mueller report conceded that Trump had not been completely exonerated by the probe. House Judiciary Committee Chairman Rep. Jerry Nadler blasted that as a “hasty, partisan interpretation of the facts.”

Some on the left are also claiming that the legal veteran, who also served as President George H.W. Bush’s attorney general a generation ago, was tainted by a memo he wrote prior to his current appointment in which he said that Mueller ought not be allowed to pursue an obstruction charge against Trump.

That’s now producing charges that Barr did a secret deal with Trump in which he obtained his office by promising to spike the Mueller probe and is bent on protecting the president regardless of the facts.

But if trying to depict Barr as a conspirator is the best shot Trump’s critics have left, they might as well give up now.

The notion that Barr would be willing to destroy his good name after many years of public service or was acting out of ambition or partisanship to come out of retirement merely to help Trump evade justice is ludicrous.

Barr’s willingness to spike any obstruction charge is rooted in some basic facts. Absent the crime of collusion, it’s hard to argue that Trump obstructed anything.

All of the “proof” also comes in the form of public statements in which Trump was expressing resentment for being investigated on a charge for which he happened to be innocent, not some secret effort to derail Mueller who was allowed to drag out the investigation for two years.

Nor is it reasonable to allege that firing FBI Director James Comey obstructed the investigation, because it continued without him. The same is true about complaints that Trump answered written questions from Mueller rather than submitting to an interview.

Democrats need to understand that the American people aren’t going to buy a campaign to demonize Barr as a proxy for Trump simply because they’re unhappy about Mueller’s paltry results. Doubling down on Russia now is bad politics as well as bad for the country.

Whether they like it or not, Democrats need to finally accept the legitimacy of the 2016 election before they can think about doing better in 2020.

Jonathan S. Tobin is editor in chief of JNS.org and a contributor to National Review. Twitter: @jonathans_tobin