It's crazy how that would have been one of the worst possible outcomes for the country. Let's say Biden loses Wisconsin by around 1,000 votes, with the election being one of the biggest polling errors in modern history (it is now too of course but people don't care much). He wins the popular vote by 3.8%, I think that comes to a 6 million vote margin. Democrats still win 222 seats in the House and the popular vote there too. Then, after two months of drama-probably even more intense than real life-the House would vote by state delegations to re-elect Trump. It would have been so divisive and so undemocratic, and just a giant mess all around. And it shouldn't have been that close anyway, because he did such a bad job in his term and is just so terrible. It does make me feel relief thinking about it.
What would make this scenario so interesting and unpredictable is that with exactly 26 R state delegations, Trump would absolutely need Liz Cheney's vote as the sole representative from Wyoming to become president.
*This assumes MN-02, PA-17, and MI-08 all stay Dem to maintain the ties in those states, which they all would on a uniform swing (MN-02 would get within 1%, though).
**Elsewhere, Malinowski would lose NJ-07 on a uniform swing that makes Biden lose Wisconsin. IA-03 and IL-14 would both be within 0.1% and go to a recount. VA-07 would have a clear Spanberger lead, but would be well within VA's 1% recount threshold. At the start of the new congress, Dems could have exactly 218 seats!
I think Cheney did endorse Trump but it would be a wild situation. Apparently the previous contingent elections were done by secret ballot, but even if some NeverTrumpers tried to argue for it I can't see that being acceptable in the modern era. Also, Democrats did not win any House races by 0.6% or less. I'm not sure how you're getting your swings.
Cheney almost certainly still supported Trump in 2020.
https://mobile.twitter.com/Liz_Cheney/status/1238577753961660417https://mobile.twitter.com/Liz_Cheney/status/1232658155785654273https://mobile.twitter.com/Liz_Cheney/status/1224902093380648960
