The bill's sponsor, Democratic Rep. Greg Harris, tearfully explained to his House colleagues that he simply didn't have the needed 60 votes after weeks of furiously lobbying his colleagues, some of whom asked for more time to gauge their constituents' support.
"I've never been sadder to accept such a request, but I have to keep my eye, as we all must, on the ultimate prize," Harris said, referring to eventual passage. "They've asked for time to go back to their districts, talk to their constituents, and reach out to their minds and hearts."
Gay marriage supporters, who had packed the House gallery in anticipation of a vote, immediately expressed their frustrations. Some shouted "Call the vote! Call the vote!" and "Shame!" Another yelled "Justice delayed is justice denied!"
Their disappointment followed months of arduous lobbying efforts by both gay-rights advocates and opponents, much of it coming from churches. The state Senate approved the measure on Valentine's Day, and Gov. Pat Quinn, a Chicago Democrat, had pledged to sign it into law. Supporters had called the bill a matter of equality and civil rights.
Jim Bennett, the regional director of Lambda Legal, one of the gay-rights groups advocating for the measure, called the lack of vote unacceptable. He said supporters of the measure have the right to know where their legislators stand on this issue.
"There is no reason why the state of Illinois, the bluest of blue states in the Midwest, cannot move forward, when neighboring Iowa and ... Minnesota have been able to figure this out," Bennett said.
The Catholic Conference of Illinois, which opposes gay marriage, said in a statement that the state's bishops were "profoundly grateful" that lawmakers "listened to their constituents and declined to consider legislation that would redefine marriage in Illinois."
When the year began, proponents were pushing to make Illinois the 10th state and first in the Midwest to adopt gay marriage, just two years after approving civil unions. But three other states – Delaware, Minnesota and Rhode Island – have since embraced same-sex marriage.
Harris was coy during the past three months about how close he was to the 60 votes needed to pass the measure. Shortly after the Senate's approval, powerful House Speaker Michael Madigan said the measure was short by about a dozen votes. But Harris later corrected that he needed less than a dozen.
Opponents of the legislation – which included some of the most powerful religious leaders in the state – had said the bill would force religious organizations to allow same-sex marriage ceremonies in their fellowship halls, parish centers and sanctuaries. The bill then was altered to state that churches would be immune from being sued should they refuse to provide their religious facilities to celebrate a same-sex wedding, but businesses, health care and educational facilities, and social service agencies were not exempt.
Some of the strongest opposition came from prominent pastors of several large black churches in the Chicago area, who fought the measure through radio commercials and robocalls exhorting parishioners to ask their legislators to vote against the measure.
Anticipation for the vote ramped up all week with protests and campaigning. One person tried to display a rainbow flag – symbol of the gay rights movement – in the chamber but it was quickly removed by guards.
Most of the attention focused on the 20 members of the House Black Caucus, most of them Chicago-area Democrats. While a few signed onto the idea publicly, a number remained undecided or avoided the question, even to the very end.
Throughout the day, Harris was seen walking away from the floor with members of the Black Caucus and talking to them at their seats.
Obama exhorted the legislators of his home state to approve the measure at a fundraising event Wednesday in Chicago.
"Here in Illinois, we've got a vote on same-sex marriage that's going to be coming up in the state Legislature," Obama told the attendees. "And I just want to say for the record it's something that I deeply support."
The intense lobbying in Springfield included appearances by Hollywood stars and Chicago's business elite. The measure cleared the Senate on Valentine's Day with the support of 33 Democrats and a single Republican.
The issue caused internal conflict among Republicans as the party works to appeal more to younger voters, minorities and women. Illinois GOP Chairman Pat Brady resigned recently after he came under criticism from some party members for expressing support for gay marriage. Conservative independent groups pledged to spend thousands of dollars against any Republican lawmakers who voted in favor of the legislation.
After the Legislature adjourned Friday, Quinn said he was disappointed.
"This is not over. The fight goes on," he said. "We will keep on fighting until marriage equality is law in Illinois."