More than 2,000 people in Dallas, Bexar, Cameron and Travis counties who used an online tool to register to vote may not be registered after all.

The Texas secretary of state's office said this week that the applications submitted through vote.org may be invalid and open to legal challenges because they contain photos of signatures instead of originals.

By the time the office announced this, about 800 of the applications had been processed in Dallas County. The voter registrar in Travis County said Thursday that his office planned to accept the nearly 1,000 applications it had received through vote.org, on the advice of the county attorney.

Given the discrepancies, what should applicants who registered through vote.org do? Experts were clear: Send in another application.

"Anyone who registered to vote using this tool needs to go online to verify whether or not you're registered," said Anthony Gutierrez, executive director of Common Cause Texas. "Just to be safe, submit another registration by mail. The process doesn't take long."

Gutierrez said Common Cause, a nonpartisan government accountability group, will lobby lawmakers to pass a bill during next year’s legislative session to allow online voter registration.

Texas, known for its strict voting laws, is not one of the 37 states that allow online voter registration. The state also has a voter identification law, which some say is necessary to prevent fraud. A legal challenge from plaintiffs who said the law discriminates against minorities and suppresses their votes ended last month.

Gutierrez said registering online is convenient and secure and would save local governments money because they wouldn't need an employee to enter the registration information.

But Arthur Fleming, past president of the Dallas NAACP chapter, said his organization has never advocated for online voter registration because of the potential for problems, such as the state's invalidation of the vote.org applications.

A June poll from the Texas Politics Project, with the University of Texas and the Texas Tribune, said 77 percent of Texas Democrats support online voter registration, compared with 41 percent of Republicans.

Jim Henson, director of the project, said people who are concerned about the status of their registration should explain the situation to their county clerk, who can answer questions and make sure they’re registered to vote in November.

The deadline to register is Tuesday. Visit this page for information on registering, what's on the ballot, how to contact your county clerk and more.