CANBERRA, Australia — Two rival bills that would lift a ban on gay marriage in Australia have been introduced into Parliament weeks after the ruling Labor Party lifted its opposition to same-sex unions.

The two bills, sponsored by lawmakers from the Labor and the Greens parties, highlight tensions between the minority government partners that undermine the chances of gay marriage ever being endorsed by Parliament.

The bills introduced Monday are essentially the same. Both place same-sex couples on the same footing as heterosexuals, while allowing religious ministers the freedom to refuse to solemnize any marriages that are inconsistent with their beliefs.

No timetable has been set for a vote on either bill.