I think you're misreading the situation. These Republicans fed up with Trump and most of the party following him, aren't about to become Democrats. You can look at the party affiliation numbers since last Nov 2020. 30% identified as republicans then, today it's 26%. They went into the independent column, they haven't become Democrats as the Democrats still have the 31% today as they did last November.

Murkowski, Romney, Cheney and whoever aren't about to caucus with the Democrats. I'd say they're more or less traditional conservatives who refuse to follow a man with no political ideology or philosophy. A traditional conservative isn't about to join the democratic party. They want to fight for their political ideals and beliefs, which Trump doesn't represent and never has. But neither does the democratic party.

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.