Meanwhile Bernie has been lying to voters for five years that he could break up banks, eliminate student loan debt, and throw 140 million people off their insurance if he holds enough rallies in Louisville, Kentucky. A mess.
This seems like a pretty disingenuous attack. As I recall, you were pretty enthusiastic about Stacey Abrams in 2018. If she had been elected Governor, would she have been able to enact all the policies that she would have liked to enact, if there were GOP control of the GA state legislature? Seems quite doubtful.
This is simply what politicians do when they campaign - they say what policies they would like to enact.
Whether it is possible for them to be enacted depends not on whether the voters elect any one politician, but on all of the various politicians that the voters elect.
Supposing that the voters elect Bernie Sanders with a GOP Senate, and the GOP Senate decides not to pass what Bernie Sanders wants to pass, that is no more his fault than it would be if the voters in GA elected Stacey Abrams, but the GOP still held a majority in the GA state legislature (probably with help from gerrymandered districts etc) and said "hell no, we are not doing what the black lady wants us to do."
The same is true for all politicians fairly universally - when campaigning, they say what they would like to do, but whether they can actually do it depends in large part on who else the voters (or the electoral system, more precisely, since most elections are not free and fair) decide to elect along with them.