DES MOINES, Iowa — With the first nominating contest of the 2020 election a day away, Democratic voters here are voicing frustration that their first-in-the-nation caucus state is the only one that still outright bans former felons from voting without prior approval from the governor.

Under Iowa law, people with felony convictions who have completed their prison sentences cannot vote unless they apply directly to the governor for the right to be restored. Voting rights advocates — and Democratic voters — say it's a major blemish on a state that prides itself on helping the nation pick its presidential candidates.

"It's embarrassing," Melissa Feilmeier-Marzen, 40, a teacher from Robins, told NBC News at a rally for Sen. Elizabeth Warren, D-Mass., on Saturday.

"Voting rights matter. And people should have voting rights no matter their past, present or future," Feilmeier-Marzen said.

Iowa became the last state with a ban on voting rights for former felons after Kentucky's newly sworn-in Democratic governor signed an executive order in December to restore voting rights to more than 100,000 people who'd been convicted of felonies.

In 2016, Terry McAuliffe, a Democrat who was then the governor of Virginia, signed an executive order that made restoring voting rights to ex-felons who had completed their sentences automatic.

And in Florida in 2018, voters approved a ballot measure that restored voting rights to people with felony convictions. The GOP-controlled Legislature later imposed restrictions on those individuals that many critics likened to a "poll tax." That law was then challenged in court, and a federal judge ruled in October to block it, at least temporarily.

That, for the moment at least, leaves Iowa as the only state with a ban in place, experts said.

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"Iowa is the worst of the worst on this policy. It is the last and only state that permanently disenfranchises people with convictions in their past without government action," said Myrna Perez, director of the voting rights and elections program at the Brennan Center for Justice in New York. "It has been out of step with the rest of the country for years, and now it's on an island on this issue."

Under Iowa law, former felons have to apply to the governor individually for their rights to vote to be reinstated. Perez and other experts said, however, that the number of former felons with access to that information and the resources and ability to go through the application process is minimal.

They also said the ban disproportionately affects African Americans, who are incarcerated at a rate five times that of white people.

According to the Sentencing Project, a criminal justice reform and advocacy group, about 24,000 former felons in Iowa are eligible to apply to have their voting rights reinstated. But only a fraction have done so.

Iowa Gov. Kim Reynolds delivers her Condition of the State address before a joint session of the Legislature on Jan. 9, 2018, at the Statehouse in Des Moines, Iowa. Charlie Neibergall / AP file

"One of the biggest challenges is that there is generally very little public education about this and very little effort by the state to inform people affected of their rights," said Marc Mauer, the group's executive director. "In a place like Iowa, there's a very modest number of people who know they can apply and who know there's a governor who is receptive to restoring voting rights."

Gov. Kim Reynolds, a Republican, has repeatedly said she wants voting rights for former felons restored. But she wants it done via an amendment to the state Constitution — which would have to be passed through the Legislature — and has ruled out signing an executive order (like the ones in Kentucky and Virginia) that might restore those rights immediately. Reynolds proposed a constitutional amendment to the Legislature last year. It passed the GOP-controlled House but died in the GOP-controlled Senate.

Reynolds, however, vowed last month to clear the backlog of applications from former felons who had applied to have their voting rights restored before the Iowa caucuses so they could participate.

On Friday, her office confirmed to NBC News that she had, in fact, completed the approval process for the more than 400 applications that had been pending since the start of the year. Reynolds' office said it received more than 800 applications in 2019 and granted 292.

Experts like Mauer, however, point out that that is "a small fraction of that overall eligible population."

In Iowa, the path on the policy has been unwieldy. The current law has been on the books for years, but in 2005, Gov. Tom Vilsack, a Democrat, signed an executive order restoring voting rights to most former felons. But in 2011, his successor, Terry Branstad, a Republican, signed an executive order rescinding Vilsack's.

Reynolds has cited the temporary nature of executive action as the primary reason she doesn't want to use it to restore voting rights for ex-felons.

Iowa Democrats said Reynolds deserves at least some plaudits for her desire to work on the issue — but they generally disapproved of her decision not to do so with executive action.

"Here in Iowa, I believe if someone has served their time and is trying to get back into society, their rights should be restored," Marcele Kaduce, 74, of Solon said Saturday at a campaign event for former Vice President Joe Biden.

Mel Schlachter, a retiree from Iowa City who is supporting Warren, said, "It's time to do it."

"The good news is that the present governor wants to change this through the constitutional amendment. The bad news is that she's unwilling to do anything herself until they do that," Schlachter said. "But ex-felons will languish because of that.

"She could do it immediately if she wanted to," he said.