HOUSTON (AP) - Opponents of Houston's new protections for gay and transgender residents have sued the city after failing to collect enough votes for a repeal referendum.

The Houston Chronicle reports (http://bit.ly/1qW4esC ) the lawsuit filed late Tuesday contests how signatures were counted for the referendum petition. It claims City Attorney David Feldman illegally verified the signatures.

Backers needed 17,269 signatures to place the repeal on the November ballot. They say they collected more than 50,000.

Feldman said Monday that less than half of the pages submitted were valid. Signers had to be verifiable as registered Houston voters. He says only 15,249 valid signatures were collected.

Feldman says his involvement didn't cross ethical or legal lines. He says he has a specific duty to interpret the law and give legal advice.