THE ANTIC behavior of Rep. Devin Nunes (R-Calif.), who was slipped classified surveillance by senior aides to President Trump, rushed to hold a news conference about it and then scurried back to the White House to brief Mr. Trump, was clumsy and clownish — but it may have accomplished its main purpose. Mr. Nunes managed to derail his own House Intelligence Committee’s investigation into the far more serious matter of Russia’s interference in the presidential election, and to distract attention from the emergence of troubling new evidence.

As the congressman’s bizarre circuit was chewed over in Washington, it emerged that Jared Kushner, the president’s aide and son-in-law, had met with an executive from a Russian bank that is on the U.S. sanctions list; former national security adviser Michael Flynn sought immunity in exchange for his testimony on his Russian ties; and experts told the Senate Intelligence Committee that Russian hacking and propaganda efforts are continuing, and have recently been directed at House Speaker Paul D. Ryan (R-Wis.) and Sen. Marco Rubio (R-Fla.).

Mark R. Warner (Va.), ranking Democrat on the Senate committee, offered an appeal to common sense: The public, he said, must “not lose sight of what the investigation is about: An outside foreign adversary effectively sought to hijack our most critical democratic process, the election for president” in order to “favor one candidate over another.” Unfortunately, Mr. Trump and willing accomplices such as Mr. Nunes have been all too effective in clouding this shocking reality and impeding effective investigation of it.

The delivery of intel to Mr. Nunes — which the White House has yet to explain — was only the latest diversionary stratagem employed by Mr. Trump and his aides. Earlier, Mr. Nunes and Senate Intelligence Committee Chairman Richard Burr (R-N.C.) were enlisted to call reporters to discount stories about contacts between Trump aides and Russia. Then Mr. Trump used a series of tweets to falsely accuse President Barack Obama of ordering a wiretap on Trump Tower. Meanwhile, as The Post reported, the administration tried to block former Justice Department official Sally Q. Yates from testifying to Congress about what she knows about the links between the Trump campaign and Moscow.

Mr. Trump is still dismissing the Russia investigation as “a witch hunt” that Democrats are using to excuse their “big election loss.” He may be right that there was no active collusion between his campaign and the Kremlin; two former senior intelligence officials with no sympathy for the president have said publicly that they were aware of no evidence of collaboration. Democrats who speak as if such links have been proved are risking their own credibility.

(Peter Stevenson/The Washington Post)

It nevertheless should be undeniable, by now, that the regime of Vladi­mir Putin brazenly intervened in U.S. politics, including by hacking the Democratic National Committee and releasing stolen material through the WikiLeaks site; that it is still trying to disrupt the political system, including by sowing fake news and faux controversies on social media; and that it is attempting to disrupt elections in other Western democracies, including France and Germany. The top priority of the president and Congress should be to fully expose this hostile assault and develop means to counter it.

Instead, Mr. Trump appears to be doing his best to confuse the public about the facts and to prevent the truth from coming out. That, of course, is Russia’s agenda — and it is the strangest and most suspicious aspect of his presidency.