Not to derail this thread from the Alaska race, but I do wonder if this is a sign that Manchin is going to get actively involved in more Senate races. Especially with the Republicans themselves nonsensically peddling the "Manchin is the only good Democrat" line or whatever, he could very easily go to certain regions and lend credibility to Dem candidates with certain types of voters.
I don't think Manchin has that kind of pull, as the kind of voters you're referring to probably are not the types to be familiar with Manchin or his brand of politics. His endorsement of Murkowski (and Collins) seems like simply a self-serving move.