DENVER—An effort to repeal Colorado’s gay-marriage ban has been abandoned by college students who won state approval to petition the idea onto ballots next year.

Gay marriage proponent Mark Olmstead of Aurora confirmed reports Thursday that he will give up an attempt to get some 86,000 signatures needed to get the question on 2012 ballots.

In July, state ballot officials gave Olmstead clearance to seek signatures to undo a gay marriage ban approved by voters in 2006. The suggested amendment would have allowed people to marry regardless of gender.

The measure didn’t have the support of prominent gay-rights groups in Colorado, which planned to instead push for a civil-unions bill in the Legislature next year.