Joe Biden trounced Donald Trump in Virginia last year; his victory margin of 10 percentage points in the state was the biggest by any candidate in a presidential contest since 1988. Despite that, Glenn Youngkin, the Republican candidate for governor, continues to feed, wink at and indulge the fiction that somehow the election was crooked, the better to cultivate his Trump-idolizing base.

It’s a pernicious lie, as well as a direct threat to U.S. democracy, and Mr. Youngkin is complicit in sustaining it. Given repeated opportunities to state the truth by shutting down conspiracists, he fudges.

Last Saturday, he attended an “election integrity" rally at Liberty University in Lynchburg, an event whose lineup of speakers suggested it would be a festival of fabrications about the 2020 election. Mr. Youngkin showed up even after his running mates on the GOP ticket, for lieutenant governor and attorney general, pulled out. No journalists were allowed, which averted the risk of awkward questions about baseless assertions.

Recently, he had been asked by a hopeful voter whether the courts might overturn the results of last year’s elections. There was a simple and truthful answer to that: No. Mr. Youngkin didn’t give it. Instead, he lamented that the “court system is moving slowly and it’s unclear,” adding a confection of words designed to give GOP partisans the impression that he also harbored such hopes.

Another voter asked the candidate about ballots cast by dead people, one of many such evidence-free conspiracy theories peddled by Mr. Trump and his acolytes. Again, Mr. Youngkin offered his sympathy and tacit agreement, suggesting that tighter rules were required to avoid a recurrence of such fraud. “When I’m governor,” he said, “we’ll be able to make some reforms.” He added: “We don’t trust our election process. We need to.”

It is precisely such weasel words, in deference to lies, that have sown the distrust in elections among Republican voters. Since becoming the gubernatorial nominee, Mr. Youngkin has acknowledged that Mr. Biden won the presidency legitimately. But he subverts that message by rolling with the fabrication of a rigged election, and proposing phony “election integrity” measures that masquerade as “reforms.”

It’s not worthwhile to speculate about whether Mr. Youngkin knows better. His background as a private equity executive contains nothing to suggest his analytical faculties were colored by a fondness for make-believe. But Mr. Youngkin, a first-time candidate, is crafting his public persona on the stump. By playing footsie with the “big lie,” he is helping to undermine faith in democracy.