(Reuters) - The American Civil Liberties Union sued Kansas officials on Thursday over what it calls illegal demands for additional proof of citizenship for people trying to register to vote when they renewed or applied for drivers’ licenses.

In a suit filed in federal court, the ACLU claimed that more than 35,000 potential voters were blocked over two years from voting because of the additional hurdle - or nearly 14 percent of all new registrants.

The Kansas law requiring documents like a birth certificate or U.S. passport for voter registration, which took effect Jan. 1, 2013, is one of numerous voter ID laws passed by Republican-led state legislatures in recent years. The ACLU alleges that Kansas goes beyond what is required by federal law.

Democrats have argued that ID laws target voters who typically support the Democratic Party, such as the young and minorities. Proponents of the measures say they are intended to prevent voter fraud.

Named plaintiffs in the Kansas suit include Ralph Ortiz, a U.S. Air Force veteran who registered to vote while renewing his driver’s license. A year later, he received a letter telling him he was suspended from voting and had to provide additional proof of citizenship.

“I joined the military to help protect American freedoms, yet now I’m being denied the most fundamental right in our democracy,” said Ortiz, 35, in a statement.

The lawsuit also named a 36-year-old Lawrence man who had been born on a now-closed Illinois military base and has not been able to find his birth certificate, and a 57-year-old Wichita woman who cannot afford the fee to get her Maryland birth certificate.

Those affected by the Kansas law are disproportionately young - 44 percent of those on the suspended voter list were between the ages of 18 and 29, the lawsuit said. Almost 54 percent were unaffiliated with any political party, the suit said.

ACLU lawyer Dale Ho said that some voters showed citizenship documents but then were told they had to submit them again.

“It’s a bit of a bureaucratic mess over there,” said Ho.

The lawsuit names Kansas Secretary of State Kris Kobach and Secretary of Revenue Nick Jordan as defendants. Craig McCullah, a spokesman for Kobach, said the office was reviewing the lawsuit and had no immediate comment.