The U.S. House of Representatives on Wednesday was poised to vote on a proof-of-citizenship requirement for voter registration, a proposal Republicans have prioritized as an election-year talking point even as research shows noncitizens illegally registering and casting ballots in federal elections is exceptionally rare.

Even if it passes the GOP-controlled House, the legislation is unlikely to advance through the Democratic-led Senate. The Biden administration also said it’s strongly opposed because it says safeguards already are in place to verify voter eligibility and enforce the law against noncitizens trying to cast ballots.

Still, the House vote will give Republicans an opportunity to bring attention to two of their central issues in the 2024 race – border and election security. They also are using Democratic opposition to the bill as fuel for former President Donald Trump’s claims that Democrats have encouraged the surge of migrants so they can get them to register and vote, which would be illegal. Noncitizens are not allowed to vote in federal elections, nor is it allowed for any statewide elections.

Republican House Speaker Mike Johnson, a key backer of the bill, said in a news conference earlier this week that the Democratic opposition means many Democrats “want illegals to participate in our federal elections; they want them to vote.”

During a speech Wednesday previewing the expected House debate, he called the vote a “generation-defining moment.”

“If just a small percentage, a fraction of a fraction of all those illegals that Joe Biden has brought in here to vote, if they do vote, it wouldn’t just change one race,” he said. “It might potentially change all of our races.”

On his Truth Social platform this week, Trump suggested that Democrats are pushing to give noncitizen migrants the right to vote and urged Republicans to pass the legislation — the Safeguard American Voter Eligibility Act — or “go home and cry yourself to sleep.”

The fixation on noncitizen voting is part of a broader and long-term Trump campaign strategy of casting doubt on the validity of an election should he lose, and he has consistently pushed that narrative during his campaign rallies this year. Last month in Las Vegas, he told supporters, “The only way they can beat us is to cheat.” It also is part of a wider Republican campaign strategy, with GOP lawmakers across the country passing state legislation and putting noncitizen voting measures on state ballots for November.

Democrats and voting rights advocates have said the legislation is unnecessary because it’s already a felony for noncitizens to register to vote in federal elections, punishable by fines, prison or deportation. Anyone registering must attest under penalty of perjury that they are a U.S. citizen. Noncitizens also are not allowed to cast ballots at the state level. A handful of municipalities allow them to vote in some local elections.

They also have pointed to surveys showing that millions of Americans don’t have easy access to up-to-date documentary proof of citizenship, such as a birth certificate, naturalization certificate or passport, and therefore the bill could inhibit U.S. citizen voters who aren’t able to further prove their status.

During a floor debate before the vote Wednesday, Rep. Joe Morelle of New York, the top Democrat on the House Administration Committee, expressed concern that the bill would disenfranchise various American citizens.

He mentioned military members stationed abroad who couldn’t show documentary proof of citizenship in person at an election office, as well as married women whose names have changed, Native Americans whose tribal IDs don’t show their place of birth and natural disaster survivors who have lost their personal documents.

Yet Republicans who support the bill say the recent unprecedented surge of migrants illegally crossing the U.S.-Mexico border creates too large a risk of noncitizens slipping through the cracks. They could purposely or inadvertently break the law to cast ballots that sway races amid narrow margins in November’s elections.

“Every illegal vote cancels out the vote of a legal American citizen,” Rep. Bryan Steil of Wisconsin, the Republican chair of the House Administration Committee, said during the floor debate.

If passed, the bill would require noncitizens to be removed from state voter rolls and require new applicants to provide documentary proof of U.S. citizenship. It also would require states to establish a process for applicants who can’t show proof to provide other evidence beyond their attestation of citizenship, though it’s unclear what that evidence could include.