Sen. Bernie Sanders said in early April that he supports allowing people who are currently incarcerated to vote.

Sanders is the first Democrat to endorse this idea, which is already implemented in his home state of Vermont.

The Senator from Vermont expanded on his stance on voting rights for incarcerated people during a CNN town hall on Monday. Sanders said he supports voting rights for all US citizens, even if they're "terrible people" — contending disenfranchising any group of Americans is a slippery slope.

Sen. Elizabeth Warren has proposed enfranchising felons who've completed their prison sentences, but has stopped short of promoting voting rights for current prisoners.

Sen. Bernie Sanders of Vermont in early April became the first Democratic presidential candidate to champion extending voting rights to people currently behind bars, and he's since been pressured on whether he even supports enfranchising people convicted of crimes like terrorism or sexual assault.

Sanders has said he supports voting rights for all US citizens, even if they're "terrible people," contending that disenfranchising any group of Americans is a slippery slope.

At a town hall in Muscatine, Iowa earlier this month, Sanders was asked whether he thought people who are incarcerated at present should have the right to vote.

"I think that is absolutely the direction we should go," Sanders replied, according to the Des Moines Register.

"In my state, what we do is separate. You're paying a price, you committed a crime, you're in jail. That's bad," he said. "But you're still living in American society and you have a right to vote. I believe in that, yes, I do."

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It's up to states whether or not current or former inmates are allowed to vote. In Vermont, felons maintain voting rights regardless of whether they're incarcerated, but it varies from state to state.

In Alabama, Mississippi, and Tennessee, a lifetime voting ban is placed on people convicted of murder or rape. Meanwhile in Iowa and Kentucky, people with felony records are barred from voting for life unless the governor personally intervenes.

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A 2016 report from The Sentencing Project, a non-profit focusing on criminal justice reform, estimated roughly 6.1 million people in the US have been "forbidden to vote because of felony disenfranchisement, or laws restricting voting rights for those convicted of felony-level crimes."

Sen. Elizabeth Warren of Massachusetts, another 2020 Democrat, has supported the notion of restoring voting rights for people with felony records who've completed their sentences, but didn't go as far as supporting enfranchisement for current prisoners.

During a CNN town hall on Monday, Sanders was asked if he'd even support enfranchising domestic terrorists such as the Boston Marathon bomber.

"If somebody commits a serious crime, sexual assault, murder, they're going to be punished. They may be in jail 10 years, 20 years, 50 years, their whole life," Sanders said in response. "That's what happens when you commit a serious crime."

"But I think the right to vote is inherent to our democracy. Yes, even for terrible people, because once you start chipping away…you're running down a slippery slope," Sanders added. "I believe even if they are in jail, they're paying the price to society, that should not take away their inherent American right to participate in our democracy."

—Cuomo Prime Time (@CuomoPrimeTime) April 23, 2019

After a follow-up question from moderator Chris Cuomo, Sanders said he was likely to be attacked by Republicans for his stance but accused the GOP of working to undermine the voting rights of marginalized groups.

"I will do everything I can to resist that," Sanders said. "This is a democracy, we have to expand that democracy."