Amending the constitution might be extremely difficult (if not impossible). But, i do wonder if there are alternatives that may not fix ALL the problems, but at least improve the situation.
The U.S. had a 'voting rights act' which forced various states to stop practices with suppressed minority votes. (Eventually the supreme court said the law was no longer needed, but then some of those states went right back to suppressing the votes of minorities again.) Congress could try passing such laws again. (Admittedly they would need a friendly supreme court to make sure they weren't struck down as unconstitutional, so Biden might have to stack the court.)
They could pass laws like:
- forcing all states to offer a vote-by-mail option, with times that ballots can be received
- Ensuring a minimum number of polling stations and advanced polling days
- Set universal ID requirements (ones that are less stringent than what many republicans want to enact)
Yes, some of these provisions go against things that have traditionally been the state's responsibility. But, as I pointed out before, the Voting rights act existed for decades (and parts were ruled as constitutional), and it also impacted the state's setup for voting.