A bill which aims to make Illinois the 10th state to legalize gay marriage cleared a state Senate committee on Thursday.

The Senate Executive Committee approved the measure, sending it to the full Senate.

However, citing missing supporters, the bill's champion in the Senate, Senator Heather Steans, a Democrat from Chicago, called off a full Senate vote. Steans said three supporters, two Democrats and one Republican, were not present to vote.

While Democrats hold a 35-24 majority in the Senate, passage remains uncertain.

The Senate adjourned its lame-duck session on Thursday, which means the House could go first in approving the measure when its special session begins on Sunday. Depending on how the House votes, the Senate could return to vote on Tuesday. New lawmakers are sworn in on Wednesday. Steans conceded that the effort in the Senate might need to wait until after the start of the new legislative session.

“This is definitely a question of when, not if,” Steans is reported as saying. “This is the right thing to be doing.”