SAN FRANCISCO (AP) - The legal groups that have led the effort to legalize same-sex marriage in California are asking to be part of a federal lawsuit against the state's gay marriage ban.

But the lawyers who brought the suit on behalf of two unmarried couples are opposing the request from the American Civil Liberties Union, Lambda Legal and the National Center for Lesbian Rights.

After previously submitting papers in support of the plaintiffs, the groups now also want to be parties in the case. They filed a motion Tuesday requesting permission to represent three gay community groups in the lawsuit seeking to overturn Proposition 8.

Last week, a judge in San Francisco put it on a fast-track to trial.

The suit's original lawyers say getting more groups involved would delay and unnecessarily complicate the proceedings.