"In this day and age, with lines growing at the polling places and people having increasingly complicated work schedules, I believe every state should allow its voters to vote early and vote absentee with no 'excuse' requirement," Feinstein said in a statement.
Besides lines, the biggest problems Tuesday had to do with voter-registration systems. Even with new electronic databases, states often dropped would-be voters from their rolls if their names or data didn't match driver's or Social Security records.
That has led advocacy groups to push for universal registration — a system used by at least 24 other countries in which all eligible citizens are automatically able to vote and permanently kept on the rolls. "This is a way of getting politics out of the voter registration system," says Wendy Weiser of the Brennan Center.
Democrats generally want to expand the voter base, while Republicans want to stop outside groups from fraudulently registering voters. As a result, universal voter registration could have bipartisan support, says Adam Fogel of FairVote.
Privacy groups might object because it likely would require proof of registration. "Some people interpret that as a national ID card," Lewis says, "and they get scared to death."