Former President Donald Trump and House Speaker Mike Johnson pitched new legislation to crack down on noncitizen voting on Friday, despite the fact the practice is already illegal and occurs rarely.

Johnson said House Republicans would introduce a bill to require documentary proof of citizenship to register to vote, speaking at Mar-a-Lago next to Trump as he seeks to fend off threats from his right flank.

“It seems like common sense, I’m sure all of us would agree that we only want U.S. citizens to vote in U.S. elections,” Johnson said, falsely suggesting that “so many people” are registering to vote when they obtain welfare benefits.

It is already a crime to register or vote as a noncitizen in all state and federal elections, though Washington, D.C., and a handful of municipalities in California, Maryland and Vermont allow noncitizen voting in local elections.

And few individuals break those laws.

“This is a crime where not only are the consequences really high and the payoff really low — you’re not getting millions of dollars, it’s not robbing a bank, you get to cast one ballot,” said Sean Morales-Doyle, a lawyer at the Brennan Center for Justice. “But what also makes this somewhat unique is that committing this crime actually entails the creation of a government record of your crime.”

Registering to vote and casting a ballot both leaves a paper trail that elected officials are required by law to routinely review. Some records are available to the public, as well.

“It’s very easy to catch, and you will get caught,” Morales-Doyle added.

The consequences are sweeping, too: noncitizens can face jail time, fines or deportation for voting illegally. Registering to vote alone could carry a five-year prison sentence, according to the Brennan Center.

On the flip side, Morales-Doyle said, requiring documentary proof of citizenship could disenfranchise millions of Americans who do not have access to passports or birth certificates.

Several states have tried to require documentary proof of citizenship in the past, but federal law currently prohibits it in federal elections. Arizona requires it for state elections, alone.

Many have investigated noncitizen voting and found little evidence of it. The Brennan Center found just 30 suspected noncitizen votes amid 23.5 million votes in 2016, suggesting that suspected noncitizen votes accounted for 0.0001 % of votes cast. Trump’s own election integrity commission disbanded without releasing evidence of voter fraud, even though he’d claimed 3 million undocumented immigrants had voted in 2016 costing him the popular vote.

But Johnson and Trump have both long advanced baseless claims about election integrity. Johnson repeatedly promoted conspiracy theories about the 2020 election and its voting machines being rigged, and he recruited Republicans to back a lawsuit seeking to overturn states where Trump lost.

For Trump, however, the proposal fuses two of his favorite talking points: immigration and voter fraud. 

“It’s the sort of story that if you’re inclined to not like immigrants in the first place feels truthy,” said Justin Levitt, a former Biden advisor on democracy issues and election policy expert. “I think that has helped it stayed politically potent even if it hasn’t gotten more true.”

Levitt said when noncitizens do vote, it’s typically a misunderstanding or mistake. He said he recalled an instance where California residents in the process of naturalizing were told they had been granted citizenship and immediately left naturalization interviews to register to vote. They had not been formally sworn in as citizens, however, and therefore were not eligible yet.