CHICAGO — A same-sex marriage bill in Illinois stalled in the Senate after gaining traction from a coalition that includes President Obama and the chairman of the state Republican Party, Pat Brady.

While the bill emerged Thursday from a Senate committee, the full chamber declined to vote on the measure, raising the prospect that final action may be delayed until a new legislative session that begins next week. Sponsors postponed the vote because some senators who support making Illinois the 10th state to legalize such unions were absent.