Most House Republicans voted to reject the certification of Joe Biden’s electoral votes. Republican state legislatures have passed this year aggressive “election integrity” laws that will make voting harder and that raise the prospect of future Republican interference in vote-counting. And, as The Post’s Amy Gardner reported Monday, a wave of new GOP candidates have made lies about election fraud the central theme of their campaigns. Some of them have already won their primary races.

At least one-third of the nearly 700 Republicans who have filed initial paperwork to run for the U.S. House or Senate next year are embracing former president Donald Trump’s “big lie” of having been cheated out of the 2020 election, as Ms. Gardner wrote. Candidates for governor, state legislature and secretary of state are campaigning on the same platform of dishonesty.

Republican leaders have argued that the nation cannot have a Jan. 6 commission and that Rep. Liz Cheney (R-Wyo.) deserved to lose her position in House leadership because telling the truth about the nation’s democracy is “relitigating the past.” Yet relitigating the past is precisely what Republicans such as state Rep. Shawnna Bolick in Arizona, U.S. Rep. Jody Hice in Georgia and House of Delegates candidate Wren Williams in Virginia want to do, except that they are rejecting the truth as they do so.

Keying off polls showing that most Republican voters believe the “big lie,” other Republican politicians have seized on “election integrity” as a kind of middle ground, allowing them to pander and wink without totally buying into the lie. But promoting election denial is not run-of-the-mill pandering, like promising ethanol policies in Iowa or heating oil subsidies in New Hampshire; this pandering could be fatal to U.S. democracy.

Not every Republican is so cynical. A Michigan state Senate committee last month released a report rebuking fraud claims in that state. The Republican leaders of Arizona’s Maricopa County have excoriated Arizona Senate Republicans for their chaotic, conspiracy-fueled “audit” of the county’s ballots.

But Ms. Cheney’s punishment, the lonely pro-democracy crusade of Rep. Adam Kinzinger (R-Ill.), and the primary challenges of other politicians such as Rep. Jaime Herrera Beutler (R-Wash.), who also has failed to toe the Trump line, encourage others to shy away from honesty. They know Mr. Trump is lying, but they say nothing, and they criticize those few, such as Ms. Cheney, who do remain honest. The “big lie” festers unchallenged until it becomes an article of faith.

Republican leaders have played footsie with dark forces on the far right under the mistaken impression that they could benefit from the enthusiasm of racists, conspiracy theorists and other extremists while maintaining control of the party, nominating traditional conservatives and promoting their long-standing policy goals. These forces have instead reshaped the party — not just on matters of policy, such as free trade, international engagement and deficit spending, but also on the most basic question of whether Americans can trust their democratic institutions. It will be up to the voters to rebuke this moral failure.