Oregon residents could consider a ballot measure next year that would require all voters to re-register to vote by 2020 and prove they are U.S. citizens.

The measure would cancel all existing registrations in 2020 unless voters re-register with documents proving they are citizens, such as a passport, birth certificate or certificate of naturalization.

James Buchal, a Portland lawyer who is one of the chief petitioners behind the effort, said in an interview that he wasn’t aware of evidence of widespread voter fraud being an issue in Oregon. He said he had heard evidence of registered voters showing up for jury duty elsewhere and then saying that they were not U.S. citizens to get out of it.

There is no evidence to suggest that widespread voter fraud is a national problem. But state Rep. Mike Nearman (R), another backer of the measure, said that there needs to be more investigation into the matter.

Nearman says the petition has around 2,000 signatures and will need to earn at least 118,000 by next year to get on the ballot. As President Donald Trump continues to stoke fears of voter fraud, the petition provides an example of the kind of measure that could gain momentum.

Critics of the proposal say it would create confusion and make it more difficult for minorities, low-income residents and older voters to vote. In 2006, the Brennan Center for Justice found that as many as 7 percent of voters didn’t have proof of citizenship.

Kate Titus, the executive director of Common Cause Oregon, said she thought it was likely the initiative would make it on to the ballot in 2018.

“The problem with these kinds of bills, which I call voter suppression bills, is they sound like they’re aimed at one thing, but the consequences are to make it more difficult for eligible voters to vote,” she said. “In this case, proof of citizenship is the core theme, so it makes it seem like it’s aimed at excluding non-citizens who are trying to vote, which we currently have no evidence that there’s a problem of that. But the impact that it will definitely have is to call into question the registrations of all currently registered voters in Oregon.”

Titus said that the measure would have a “chilling” effect on voter registration because many people lacked the documentation and time to go through the process of registering to vote all over again.

“For people who have a driver’s license, it’s easy to think, well doesn’t everybody have a driver’s license, or for people who have a passport, doesn’t everyone have a passport, but in fact, many people don’t.”

Last year, a federal appeals court blocked efforts in Kansas, Georgia and Alabama to get voters to show proof of citizenship before voting.

Nearman said he didn’t see why the law would make it more difficult for certain Oregonians to vote.

“I don’t know why a minority would be less likely to go down and re-register. I mean there’s not anything that has to do with skin color or even culture or anything like that that makes it less likely to register to vote,” he said. “If you’re not working, that’s not everybody who’s poor, I get that, but if you’re not working, I’d think you’d have even more time to go down to the county clerk or to the DMV and register to vote.”

Research has found that states that require voters to present an ID have depressed turnout among minority voters.

Buchal noted that the measure provided accommodation for people who didn’t have documentation proving they were citizens. But he suggested that people who couldn’t find the time to go through the process of re-registering didn’t deserve to vote.

“If they don’t care enough to get re-registered, I don’t care enough about their vote,” he said.

Last year, Oregon was the first state in the country to implement automatic voter registration, which automatically registered over 225,000 voters. Oregon election officials have said there is no evidence of widespread voter fraud in the state.