>> i've been voting for many, many years, and i've never missed a vote. >> reporter: thompson considers voting a duty. he fought in world war ii for the right to vote and other freedoms. decades later he fears the state's enough election law could prevent him from voting for the first time in his life. thompson has to either provide his social security number or driver's license number that matches his registration record with the county or state. >> that's because he registered to vote in the 1940s and they didn't require that. >> reporter: because he cannot add his driver's license information to the registration record, his mail-in ballot application was denied twice and he said harris county never notified him. >> there's going to be a lot of people who are going to vote. >> his daughter said she's even tried contacting the county and state to add her dad's license number to the registration file. >> we know it's a new law. we'll be happy to correct it.