I am not sure Congress can make rules about voting at all. The Constitution leaves voting to the states. And the next Congress will be a result of the great wave of vote harvesting, vote addition and vote losing that will occur in both the Presidential and the Congressional elections.I trust Trump has something up his sleeve to negate the worst effects of Democrat vote manipulation but if he does not then the Democrats may well “win” all up and down the ballot.
One way or another, ballot harvesting must become illegal. The feds have limited jurisdiction pertaining to individual states voting procedures, but I believe they do have some as they relate to national elections, iirc. If it’s too limited, new legislation is mandatory.