This presidential campaign, former President Donald Trump and other Republicans have been repeating the false narrative that Democrats are purposefully letting migrants into the country so they will vote.

There’s no evidence for the claim, which echoes a racist conspiracy theory known as the “great replacement.”

In fact, allegations about voter fraud and noncitizens have been floating around American politics for more than a century.

The GOP has made it a legislative priority to update federal law to require documentary proof of citizenship to register to vote in federal races. Opponents point out that millions of eligible voters — about 1 in 10 adult U.S. citizens, according to one recent survey — don’t have ready access to documents that prove their citizenship, such as a birth certificate or passport, and would face hurdles to vote.

Here are 6 things to know about the false narratives circulating.

There are severe penalties for noncitizens who illegally try to vote

It’s illegal for people who are not U.S. citizens to vote in federal or state elections. And the federal voter registration form asks registrants to affirm, under penalty of perjury, that they are eligible citizens. The form warns those who make false statements could be fined, imprisoned or deported. Noncitizens who register to vote can also lose the ability to ever become U.S. citizens.

Voting rights advocates say these penalties have worked as effective deterrents. “Anybody who is on a green card or attempting to get citizenship in America, they are not trying to be arrested or to be tossed out of the country,” said Sylvia Albert, the director of voting and elections for Common Cause.

Election officials regularly verify voter registration information and remove ineligible voters from voter rolls. Some states verify citizenship by cross-checking voter information with other databases, such as state motor vehicle data or the federal SAVE database. Election officials must be careful not to mistakenly remove eligible voters from voter rolls, since some databases may be outdated and may not show if an immigrant has become a naturalized citizen. Such errors resulted in large numbers of eligible citizens wrongly flagged for removal in Texas in 2019.

Available data shows noncitizen voting is incredibly rare

After the 2016 election, the Brennan Center for Justice, which advocates for voting rights, surveyed local election officials in 42 jurisdictions with high immigrant populations and found just 30 cases of suspected noncitizens voting out of 23.5 million votes cast, or 0.0001%.

The Brennan Center survey did not include North Carolina, where a state audit after the 2016 election found 41 cases of green card holders who voted out of nearly 4.8 million votes in the state. The same report said many of the noncitizen voters had been misinformed that they could vote.

Georgia Secretary of State Brad Raffensperger launched an audit in 2022 that found over the previous 25 years, fewer than 1,700 people believed to be noncitizens had attempted to register to vote. None were able to cast ballots.

After a federal trial last year over Arizona’s documentary proof of citizenship laws, the federal judge concluded, “though it may occur, non-citizens voting in Arizona is quite rare, and non-citizen voter fraud in Arizona is rarer still.”

While the conservative Heritage Foundation has actively promoted claims about the risk of noncitizens voting this campaign season, its own data suggests how rare these cases are. The Washington Post reviewed a Heritage database of voter fraud cases and found 85 cases relating to allegations of noncitizens voting between 2002 and 2023.

The American Immigration Council, which advocates for immigrant rights, also analyzed the Heritage data and found most noncitizen voting cases involve legal immigrants and many had been incorrectly told they could vote. That analysis found only 10 cases involving undocumented immigrants since the 1980s. Heritage has said the database is just a sampling of fraud cases and is not comprehensive.

Flawed studies have fueled false claims

A widely contested 2014 paper by researchers at Old Dominion University has fueled exaggerated claims about noncitizen voting rates. The study, which was led by political scientist Jesse Richman, drew its conclusions from an online survey known as the Cooperative Election Survey. A small number of respondents had indicated they were noncitizens and that they had voted. Richman’s paper used that data to estimate that 6.4% of noncitizens voted in 2008.

But that estimate immediately came under fire. The developers of the CES survey wrote a rebuttal, detailing how Richman’s research was methodologically unsound because the small subset of people who reported being noncitizen voters could easily have been citizens who had simply selected the wrong box.

Nevertheless, Trump seized on and distorted Richman’s estimates to fuel false claims in 2016 that millions of noncitizens had illegally voted. In the aftermath, some 200 fellow political scientists wrote an open letter rejecting the 2014 paper. That didn’t stop the website Just Facts from publishing a report in May based on the paper’s discredited estimates. That report made the disputed claim that 10% to 27% of noncitizens are illegally registered to vote, which went viral on X and was cited in congressional testimony.

Richman has since revised down his estimate for national noncitizen voter registration rates to just under 1%, and participation to half a percent.

A small number of localities allow noncitizens to vote in municipal races only

Washington, D.C., and a small number of municipalities in California, Maryland and Vermont do allow noncitizens to vote in some local elections, such as city council or school board races. But so far, turnout has been low from this population. Noncitizens are still barred from voting in federal and state elections in all of these places, and there are systems in place to ensure they do not receive ballots for those other races.

Most people who arrived at the border in recent years have no path to citizenship

One false narrative this campaign season suggests that the people who arrived at the U.S.-Mexico border during the Biden administration can quickly become citizens and vote legally. But the vast majority of migrants have no path to citizenship. For the minority who will ultimately be granted asylum, it often takes more than a decade from the time they enter the country to go through all the steps to win their cases and ultimately naturalize. Furthermore, changes to asylum protocols during the Biden administration have made it harder to pursue asylum in this country and eventually become a citizen.

Misleading claims about noncitizens voting can undermine confidence in the 2024 election

By focusing on baseless allegations about noncitizens voting in the upcoming election, Trump and his allies appear to be laying the groundwork for potentially contesting the election.

“You can absolutely bet if Trump loses, he will claim there was widespread noncitizen voting without any evidence whatsoever,” David Becker, the executive director of the Center for Election Innovation and Research told NPR last month. “And that is going to incite anger and potentially violence.”