A gay marriage bill arrived in the Illinois Senate on Thursday tacked on as an amendment to a rental car bill.

The unusual vehicle became a necessity after a stand-alone bill failed to clear a critical committee on Wednesday night. A solid wall of opposition from Republican lawmakers coupled with key absences among Democratic supporters killed the effort.

Supporters quickly regrouped, calling the loss a setback, not a defeat.

The bill's champion, Senator Heather Steans, a Democrat from Chicago, attached the marriage equality measure as an amendment to a bill already scheduled for a committee vote, House Bill 4963, which deals with the automobile rental industry, Chicago gay weekly Windy City Media Group reported.

The Senate's lame-duck session, which includes outgoing members, is scheduled to end Friday. House members will convene their 3-day special session on Sunday. A new legislative session begins Wednesday, January 9.

Meanwhile, Pat Brady, the chairman of the Illinois state Republican Party, on Wednesday endorsed the effort to make Illinois the 10th state to extend marriage rights to gay and lesbian couples.

“More and more Americans understand that if two people want to make a lifelong commitment to each other, government should not stand in their way,” Brady told the Chicago Sun-Times. “Giving gay and lesbian couples the freedom to get married honors the best conservative principles. It strengthens and reinforces a key Republican value – that the law should treat all citizens equally.”