Since Sen. Bernie Sanders declared that all people incarcerated should be permitted to vote, the idea has divided the Democratic presidential field. But now 73 civil rights and liberal advocacy groups have signed a letter endorsing the Vermonter's view.

"Felony disenfranchisement is not just anti-democratic and bad for public safety, it is an unpopular practice that sprang from the most shameful era of American history, a vestige of our past wildly out of step with international norms. And now is the moment for its abandonment," reads the letter, which was posted by The Huffington Post.. "This growing movement against felony disenfranchisement is a promising endorsement of American values, but it raises a key question: Why disenfranchise people in prison to begin with? Why not let them continue to vote while they are incarcerated?"

Sen. Elizabeth Warren and Sen. Kamala Harris say they're open to the idea of letting all prisoners vote, while former Rep. Beto O'Rourke and former HUD Secretary Julian Castro say they're open to prison voting by nonviolent felons. The rest of the field seems united behind restoring the franchise to felons as soon as they get out of prison. (President Trump is vehemently opposed to letting anyone vote from behind bars.)

Thanks to a wave of changes in the past two decades, most notably in Florida last year, all but five states allow convicts to vote at some point after they are released, though the policies vary widely and the strings attached in many places can be highly difficult to circumvent.