This. They need to attack him on his extremism.
I'm not certain that will work either. Republicans think Brandon, the guy who spent an entire Senate career shilling for DuPont and credit card companies, is a communist who must Go. They'll come up with whatever justification to keep voting for a Republican Party that keeps moving further and further to the right.
The Dems have no infrastructure at the state and local levels. They have no organization. They wasted Clinton's trifecta, Obama's supermajority trifecta (with a majority if governorships, which everyone forgets), and they're wasting Biden's trifecta in such a way that makes Obama from 09-10 look productive. They couldn't flip one statehouse in 2020 and took a big victory lap anyway with their Senate "Majority" and a president who barely beat a guy who admitted on tape that he purposefully ignored COVID. They have a major disconnect with their base. Until they completely clean house and start building a real party like the Republicans did in the 60s when they were in the wilderness, their only hope in Wisconsin is to increase voter turnout in Milwaukee/Madison and hope for the best.