The constitution puts 'voting' in the states hand. Voting is not a federal issue. Fix your state.
It also guarantees each state a republican form of government. A rather strong case can be made that, with the active refusal of the Wisconsin Democratic Party (through Governor Jim Doyle's vetoes of measures to fix the voting system and the Democrat-controlled prosecutorial system's refusals to enforce what few laws attempt to guarantee the sanctity of said system), Wisconsin no longer enjoys a republican form of government.
We need to fix this problem anyway we can.
If we can do it state by state, fine.
If the quickest way to do it is by passing a federal law, we should.