Former President Donald Trump turned to one of his favorite themes on Friday — the specter of immigrants improperly voting in federal elections. House Speaker Mike Johnson came to the former president’s Florida compound to announce that he would introduce a bill to stop those who are not citizens from voting in elections.

Trump has made baseless claims about this subject before, like in 2016, when he blamed his loss of the popular vote on voting by immigrants, and then appointed a commission to investigate the issue. It disbanded without identifying a single case of a noncitizen casting a vote.

He and other Republicans have recently revved up their conspiratorial claims about the issue with the influx of migrants across the southern border under Biden, contending Democrats are letting them in to add them to the voter rolls.

The theory involves two complicated subjects, immigration and voting, but it’s actually very simple. There isn’t any indication that noncitizens vote in significant numbers in federal elections or that they will in the future. It’s already a crime for them to do so. And we know it’s not a danger because various states have examined their rolls and found very few noncitizen voters.

To be clear, there have been cases of noncitizens casting ballots, but they are extremely rare. Those who have looked into these cases say they often involve legal immigrants who mistakenly believe they have the right to vote.

Johnson tried to address this, saying that “we cannot wait for widespread fraud to occur.” But one prior crackdown on purported noncitizen voting also risked striking thousands of actual citizens from the voting rolls.

Here’s why noncitizen voting isn’t a real danger to the integrity of federal elections and the risks of changing federal law.

WHAT’S THE LAW?

Federal law requires all voter registration forms to advise those signing up that they have to swear under penalty of perjury that they are a U.S. citizen. That has generally worked. Immigrants who aren’t citizens especially don’t want to violate the law because it could jeopardize their ability to remain in the country or become citizens.

Some Republicans have long complained that federal laws don’t require additional checks on voter eligibility. Johnson vowed to introduce legislation requiring proof of citizenship before allowing someone to register to vote, but he provided no further details. It’s likely that such legislation wouldn’t make it out of the Democratic-controlled Senate, and its main impact would be to use it as a talking point against Democrats during the campaign.

One reason Democrats are wary is that when Texas tried to root out noncitizen voters in 2019, the effort ended up wrongly flagging tens of thousands of U.S. citizens as being ineligible to vote. A federal judge blocked Texas from carrying out the law and the then-secretary of state resigned.

That shows the risks of adding new identification checks to catch something that very rarely happens.

WHAT’S THE EVIDENCE THAT THIS ISN’T A PROBLEM?

All available evidence shows that noncitizen voting in federal elections is incredibly rare. It’s illegal for people who aren’t U.S. citizens to vote in federal elections, but it is legal for them to vote in local elections if the jurisdiction allows it. A small number of local jurisdictions, such as San Francisco and the District of Columbia, let immigrants who haven’t become U.S. citizens vote on races for school board and city council.

Let’s look at some conservative-leaning states to see if noncitizen voting is an issue. First, we’re talking about “noncitizen” voting, not voting by immigrants. That’s because some immigrants have become naturalized U.S. citizens and under the Constitution have the same ability to cast a ballot as those born here.

In 2016, North Carolina audited its elections to make sure no one voted improperly. It found that 41 legal immigrants who had not yet become citizens cast ballots. That’s out of 4.8 million votes cast. Those illegal votes didn’t make a difference in a single election in the state, even the smallest local race, according to the state’s election board. Trump’s Department of Justice later filed criminal charges against 19 immigrants for illegally voting in North Carolina.

In 2022, Georgia Secretary of State Brad Raffensperger, a Republican, conducted an audit of his state’s voter rolls specifically looking for noncitizens. His office found that 1,634 had attempted to register, but election officials had caught all the applications and none were actually registered to vote.

The Brennan Center for Justice, a liberal group, surveyed 44 election officials in some of the most populous and immigrant-heavy jurisdictions in the country after 2016, including Arizona, California and Texas. It found only about 30 incidents of a possible noncitizen voting out of 23.5 million votes cast in those places.

One researcher used internet poll data to extrapolate the number of noncitizens voting and concluded there must be more casting ballots than the reviews have caught. Trump cited his work in 2016, but even that researcher, Professor Jesse Richman of Old Dominion University, has said Trump misused his work and that there is no evidence noncitizen voting was high enough to swing a state against the former president.

IS ANYONE ELSE CHANGING LAWS ON THIS?

The Voting Rights Lab, a left-leaning group that tracks voting legislation, says that since the 2020 election and Trump’s lies about losing because of fraud, nine states have implemented new laws to further block noncitizen voting and 16 are currently considering additional provisions.

That tally includes Texas, where the Republican-controlled legislature passed a sweeping voting bill in 2021 that revived the provision that had earlier led to tens of thousands of U.S. citizens erroneously being flagged as illegal voters. Civil rights groups have again sued to block it. The Republican National Committee, which Trump brought under his control recently, is arguing in court to keep the provision.