A close U.S. Senate race in Texas between Democrat Beto O’Rourke and Republican Ted Cruz could be swayed by whether people are actually able to cast their votes.

On Wednesday, Secretary of State Rolando Pablos rejected 2,400 registrations, and those voters will have to register properly before Tuesday. Those affected, along with others across the country, registered on Vote.org by sending their voter information to the organization, which then sent completed forms to county voter registrars.

“That’s not allowed in Texas,” Texas secretary of state spokesperson Sam Taylor said . “You can’t affix a picture of a signature to an application. That opens up a wide range of possible fraud and abuse.”

In Travis County, though, where Austin is located, voter registrar Bruce Elfant said the state law made the online registrations legitimate, according to the office’s legal counsel.

Vote.org founder Debra Cleaver wrote ,“Vote.org exists solely to increase turnout. The Texas secretary of state does not appear to share this goal. He is actively choosing to reject thousands of lawfully submitted forms only days before the deadline, in a state with several highly competitive elections,”

The Brennan Center for Justice is keeping tabs on a number of states, including Texas, in regard to restrictive voting policies like gerrymandering, illegal voter purges and rigid voter ID laws.

“The outcomes are going to depend not only on the candidates and the voters’ choices, but also on whether our voting system is doing its job. It’s got to allow eligible Americans to cast their votes, and it must protect the accuracy and fairness of the results,” said Wendy Weiser , the director of the Democracy Program at the Brennan Center.

“Texas voters continue to face obstacle after obstacle just to participate in the democratic process. Millions of eligible voters remain shut-out of the democratic process, a disparate number of whom are young, poor, and people of color,” according to the Texas Civil Rights Project.

Those living in Texas are not allowed to vote if they are on probation or parole, but organizers within the state are joining a national movement to push for voting rights for the formerly incarcerated. “This is an entirely new voting bloc,” said a Texas community organizer, Steve Huerta. “It’s a political game-changer for struggling communities.”

One formerly incarcerated woman, Crystal Mason , is facing up to five years in prison for voting in the 2016 presidential election. Mason was previously convicted of tax fraud and spent five years in prison. She was living in Fort Worth on supervised release and did not realize she was not allowed to vote.

“Black people in Fort Worth hear about her case and they understand that they are not welcome in the voting booth,” her lawyer said.

“There are no downsides to online voter registration—unless, of course, your goal is to suppress voter turnout,” Vote.org’s Cleaver wrote. “We hope that this isn’t the case, and look forward to Texas joining the 38 other states that have taken steps to secure and modernize their voter registration solutions.”