I agree with most of what you said. Now there was a massive surge all around. There was a difference, independents which made up 31% of those who voted in 2016 fell to 26% in 2020. Republicans and democrats increased. Republicans from 33% to 35% of those who actually voted over 2016 and democrats from 36% to 38%. It was independents in those close or swing districts that made the difference. They voted 41% for Trump, but 48% nationwide for Republican congressional candidates. The actual independent vote was 48-48 with 4% voting third party. I don't have the figures at hand for the districts the GOP switched, but just going by the national numbers, it seems to me the independent vote made the difference in losing those 13 seats. Not a surge or increase in Republican voters, the Democrats matched that in 2020.

Trump wasn't going to be reelected. I'm surprised he managed 46%. But that percentage is the same Trump received in 2016. The difference is Biden received 52% of the vote compared to Hillary's 48%. A lot fewer voters voted third party in 2020 compared to 2016. 6% voted third party in 2016, 2% in 2020. Biden won most of those who didn't vote third party this time around. There you have it, those who voted third party protesting the two choices of Trump and Clinton in 2016, decided on Biden in 2020. The difference in being a likable candidate and not being liked or being disliked as both Trump and Hillary were.

It's easy to understand independents voting for Biden, the likability factor. Only 30% of independents liked Trump as a person, 59% disliked him as a person. Biden, 43% liked him as a person, 45% disliked him. Independents going to Biden by 13 points is a no brainier. But what about congress, why would someone vote Biden for the presidency, then Republican for congress?

I have a theory, Only 16% of independents approved of the job congress was doing back in Nov 2020, a massive 63% disapproved. the Democrats controlled the house. Although liking Biden, disliking Trump, independents disliked or didn't approve of congress. Hence voting for Biden, then Republican for congress since the democrats were in-charge of the House. More against the party in power. But the massive turnout by both major parties faithful somewhat mitigated independents voting against the party in power resulting in a loss of 13 seats.

It might be as simple as the disliked of Trump drove voters to vote for Biden, the disapproval of congress drove some of those same Biden voters to vote Republican for congress. It's a theory. I'll add than in November 2020, independents viewed both major parties about the same, 33/63% favorable/unfavorable for the Democratic Party, 34/62% favorable/unfavorable for the Republican Party.

So when you disapprove you vote against the party in power, in this case the Democratic controlled house. Just a theory.

It's high past time that we start electing Americans to congress and the presidency who put America first instead of their political party. For way too long we have been electing Republicans and Democrats who happen to be Americans instead of Americans who happen to be Republicans and Democrats.