It comes on the same day state lawmakers returned to Springfield, five months after legislation to legalize gay marriage stalled in the Illinois House. Same-sex marriage is legal in 14 states and in the District of Columbia.
"The time for marriage equality has come. This is our hour," said Ill. Gov. Pat Quinn.
Returning to Springfield, the governor and most of Illinois' statewide elected officials put aside fiscal issues and called on the House of Representatives to vote on the same-sex marriage bill passed earlier this year by the Senate.
"It is about time that the Illinois House of Representatives passes marriage equality," said Ill. Atty. Gen. Lisa Madigan.
Outside, during a chilly rain, over 1,000 bused-in demonstrators heard politicians make marriage equality a fall session priority.
"Make it happen because it's the right thing to do," said Ill. Comptroller Judy Baar Topinka.
"We'll have a chance to validate what we call the 'Land of Lincoln,'" said Sen. Dick Durbin.
But State Rep. John Cabello expected a different fall session priority: the state's $100 billion unfunded pension debt and billions in unpaid bills.
"I think we need to get our financial house in order before we start dealing with any other social issue," said Cabello.
"This issue, to me, is about nothing more than love," said Rep. Ken Dunkin, (D), Chicago.
Lawmakers do not expect a vote on gay marriage until the first week of November. The governor, who has warned against other bills becoming distractions, has made an exception for marriage equality.
"Anytime there is an issue about rights of people, that deserves important consideration, that's exactly what we're doing here at this hour," Quinn said.
Five months after the legislation stalled in the Illinois House, hundreds turned out for the "March on Springfield," with many waving signs and flags in support. Also present were some of the state's top elected officials, including Durbin, Madigan and Quinn.
Quinn described the legislation as the "most important civil rights measure" facing the state.
Legislators returned to work with the potential for several hefty issues on the agenda, including ending gridlock on the state's nearly $100 billion pension problem, mandatory minimum sentences for gun crimes and incentives for companies to stay in Illinois.
But on Tuesday activists' focus remained on the gay marriage issue. Those who oppose it - including mega churches in the Chicago area - vowed to protest the issue in Springfield on Wednesday, starting with a prayer vigil.
Earlier in the year, a same sex marriage bill passed the state Senate but stalled in the House, where it needs 60 votes for passage. House Speaker Michael Madigan said in late September that about a dozen votes were still needed.
The bill's main sponsor, Rep. Greg Harris, a Chicago Democrat, has been mum on the vote count or when the matter is expected for a vote.
"I'm keeping an open mind," he said.
Meanwhile, advocates have said there's been significant progress. After the matter wasn't called for a vote in the House, activists and gay rights groups revamped their campaign by hiring a top union lobbyist, organizers across the state and the former chairman of the Illinois Republican Party.
"We're within striking distance, but I'm not making a prediction because were promised this was going to happen in May," said Chicago gay marriage advocate Rick Garcia. He estimated there were about 55 "yes" votes.
Not in attendance at Tuesday's rally was House Speaker Michael Madigan, who supports the measure but has yet to have the bill called in his chamber.
"Speaker Madigan, put your House in order," one sign at the rally read.
Illinois allowed civil unions in 2011. There are now 14 states, plus Washington D.C., that allow gay marriage.
However, the measure has been fought hard by church groups, notably high-profile pastors around Chicago who argue that marriage should remain between a man and a woman. A coalition of pastors has released robocalls detailing their arguments and citing Scripture.
The Associated Press contributed to this report.