republicans uniformly oppose it. in practice it's the issue on which their supposed libertarian ideology is the most transparently phony (if the deficit spending, anti-gay fervor, religious power grabs, opposition of voting rights, etc weren't clear enough anti-personal-freedom stances for you), they literally held complete and total political power in the US during the first couple years of Trump and didn't do shit, and they'll vote lockstep against it if democrats bring it up.

and on the flip side some democrats aren't great about it either, but it's far from the lockstep opposition on the republican side.

personally I think democrats are fairly likely to bring it up as an easy victory lap before the 2022 elections but it's highly likely that republicans will filibuster it anyway to prevent democrats from "getting an easy win" . and that's about the state of the things - republicans are just 100% against it and democrats are tepidly for it but don't really have the political control to break lockstep opposition, even if they were agreed within their own party. It's easier to work at a state level but obviously that leaves huge problems with federal enforcement and various legal logjams.

it's largely a problem of republicans, if there were only a few republicans willing to cross the aisle it could probably pass, but it's more important that democrats be denied political "wins" than to do what's good for their voters, and what their voters overwhelmingly want. Like I said, probably look for it to be brought up sometime in 2022, unless democrats lose their senate majority in the meantime in which case probably 5-10 more years (republicans ain't gonna do it, just like they didn't under trump).

would be the easiest possible "crossing the aisle" ever, if republicans were the least bit interested in good governance, but they're not.