Democrats have been consumed for two years with a flimsy conspiracy theory aimed at delegitimizing a presidential election they lost.

But it's over now. An exhaustive federal investigation just put the nail in the coffin of the collusion delusion.

If the Democrats and our major media are capable of shame, they will be chastened by this experience.

Special counsel Robert Mueller, backed by a team of 40 FBI special agents, analysts, and other experts, issued more than 2,800 subpoenas and 500 search warrants, and interviewed 500 witnesses. The conclusion, as summarized by Attorney General William Barr: “ The Special’s Counsel investigation did not find that the Trump campaign or anyone associated with it conspired or coordinated with Russia in its efforts to influence the 2016 U.S. presidential election."

Underlining Barr's conclusion, Mueller has served up no new indictments. This should finally put to bed the ubiquitous and never-ending speculation that became a substitute for news reporting all day, every day on some cable news networks for the last 22 months.

Ever since May 2017, if you found FOX News to be too pro-Trump, you could always turn to CNN or MSNBC and be told with great certainty, on almost any evening and for almost any reason, that "the walls are closing in" and that Trump's days were numbered. Night after night, this was the story.

Now, that show is over. It was all fake news.

Although Mueller's report is less conclusive on the question of obstruction of justice, Barr's letter adds that, based on that report, "Deputy Attorney General Rod Rosenstein and I have concluded that the evidence developed during the Special Counsel's investigation is not sufficient to establish that the president committed an obstruction-of-justice offense."

The conspiracy theory at play here was always far-fetched. It combined one upsetting reality — Russia sowed discord among Americans by a variety of means during the 2016 election — with a bad joke that Trump made in rhetorically asking Vladimir Putin to produce the emails Hillary Clinton had hidden from U.S. authorities. The virtue of this theory was that it absolved Democrats of the obligation of wrestling with the reasons behind their 2016 loss.

Barr's summary wasn't totally exculpatory of Trump, of course. On the question of obstruction, Barr noted that Mueller found evidence pointing in both directions. We've repeatedly noted in this space the destructive nature of Trump's impatience regarding this investigation. He should have waited it out calmly, instead of publicly leaning on investigators and witnesses, because the theory of the case against him was always paper-thin, as we now see clearly.

Of course, the conclusion of Mueller's report doesn't mean the end of investigations into Russia and collusion. It only means the end of the professional, nonpartisan investigations into Russia and collusion.

House Democrats will use their subpoena power to interview the same witnesses and rake over the same coals. Congressional oversight is an important function. There's plenty of stuff Democrats could look into, regarding Trump's business dealings, for instance. But the Russia investigation was the only investigation that offered them what they wanted, the chance to delegitimize Trump's election by attributing it to a foreign conspiracy.

That charge has been investigated exhaustively and debunked. Can the Democrats move on?