Here’s what we know about American politics: The Republican Party is stuck, probably irreversibly, in a doom loop of bizarro. If the Trump-incited Capitol insurrection didn’t snap the party back to sanity — and it didn’t — nothing will.

What isn’t clear yet is who, exactly, will end up facing doom. Will it be the G.O.P. as a significant political force? Or will it be America as we know it? Unfortunately, we don’t know the answer. It depends a lot on how successful Republicans will be in suppressing votes.

About the bizarro: Even I had some lingering hope that the Republican establishment might try to end Trumpism. But such hopes died this week.

On Tuesday Mitch McConnell, the Senate minority leader, who has said that Donald Trump’s role in fomenting the insurrection was impeachable, voted for a measure that would have declared a Trump trial unconstitutional because he’s no longer in office. (Most constitutional scholars disagree.)

On Thursday Kevin McCarthy, the House minority leader — who still hasn’t conceded that Joe Biden legitimately won the presidency, but did declare that Trump “bears responsibility” for the attack on Congress — visited Mar-a-Lago, presumably to make amends.

In other words, the G.O.P.’s national leadership, after briefly flirting with sense, has surrendered to the fantasies of the fringe. Cowardice rules.

And the fringe is consolidating its hold at the state level. The Arizona state party censured the Republican governor for the sin of belatedly trying to contain the coronavirus. The Texas G.O.P. has adopted the slogan “We are the storm,” which is associated with QAnon, although the party denies it intended any link. Oregon Republicans have endorsed the completely baseless claim, contradicted by the rioters themselves, that the attack on the Capitol was a left-wing false flag operation.

How did this happen to what was once the party of Dwight Eisenhower? Political scientists argue that traditional forces of moderation have been weakened by factors like the nationalization of politics and the rise of partisan media, notably Fox News.

This opens the door to a process of self-reinforcing extremism (something, by the way, that I’ve seen happen in a minor fashion within some academic subfields). As hard-liners gain power within a group, they drive out moderates; what remains of the group is even more extreme, which drives out even more moderates; and so on. A party starts out complaining that taxes are too high; after a while it begins claiming that climate change is a giant hoax; it ends up believing that all Democrats are Satanist pedophiles.

This process of radicalization began long before Donald Trump; it goes back at least to Newt Gingrich’s takeover of Congress in 1994. But Trump’s reign of corruption and lies, followed by his refusal to concede and his attempt to overturn the election results, brought it to a head. And the cowardice of the Republican establishment has sealed the deal. One of America’s two major political parties has parted ways with facts, logic and democracy, and it’s not coming back.

What happens next? You might think that a party that goes off the deep end morally and intellectually would also find itself going off the deep end politically. And that has in fact happened in some states. Those fantasist Oregon Republicans, who have been shut out of power since 2013, seem to be going the way of their counterparts in California, a once-mighty party reduced to impotence in the face of a Democratic supermajority.

But it’s not at all clear that this will happen at a national level. True, as Republicans have become more extreme they have lost broad support; the G.O.P. has won the popular vote for president only once since 1988, and 2004 was an outlier influenced by the lingering rally-around-the-flag effects of 9/11.

Given the unrepresentative nature of our electoral system, however, Republicans can achieve power even while losing the popular vote. A majority of voters rejected Trump in 2016, but he became president anyway, and he came fairly close to pulling it out in 2020 despite a seven million vote deficit. The Senate is evenly divided even though Democratic members represent 41 million more people than Republicans.

And the Republican response to electoral defeat isn’t to change policies to win over voters; it is to try to rig the next election. Georgia has long been known for systematic suppression of Black voters; it took a remarkable organizing effort by Democrats, led by Stacey Abrams, to overcome that suppression and win the state’s electoral votes and Senate seats. So the Republicans who control the state are doubling down on disenfranchisement, with proposed new voter ID requirements and other measures to limit voting.

The bottom line is that we don’t know whether we’ve earned more than a temporary reprieve. A president who tried to retain power despite losing an election has been foiled. But a party that buys into bizarre conspiracy theories and denies the legitimacy of its opposition isn’t getting saner, and still has a good chance of taking complete power in four years.

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