I mean yes, it is literally impossible for these people (at least Manchin) to win without significant Republican support. Like, probably 30-40% of Manchin's voters are also Trump voters. That isn't an excuse as much as it is a mathematical fact.

And it's also demonstrably true that moderate Republican voters do cross over and vote for Democrats sometimes, just as some moderate Democrat voters cross over and vote Republican. Joe Manchin won because large numbers of Republicans crossed over. Susan Collins won because large numbers of Democrats crossed over. Again, not an excuse, just historical fact. A lot of leftists don't like to hear that "challenging your own party generally does get you crossover votes" fact, but that doesn't make it less true.

It doesn't let Manchin off for the shit he's pulling, of course.