SPRINGFIELD, Ill. (AP) — An Illinois House committee narrowly endorsed legislation to legalize gay marriage Tuesday, setting up a showdown on the House floor that could come in a matter of weeks.

The House Executive Committee’s 6-5 approval moves the measure to the floor. Approval there would likely mean Illinois would become the 10th state to OK same-sex marriage, because Democratic Gov. Pat Quinn says he will sign the legislation.

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Chicago Democratic Rep. Greg Harris says his bill is a matter of treating gay couples and heterosexual couples equally under the law.

“What same-sex couples in Illinois want for their families is just what you want for your families,” Harris told the committee late Tuesday night.

Tuesday’s vote was split along party lines. GOP lawmakers opposed the measure despite its endorsement by state Republican Party Chairman Pat Brady. Some party faithful want Brady ousted because of his support of the issue.

Yet the vote coincided with news that prominent Republicans and retired military leaders are among those who will ask the U.S. Supreme Court to support marriage equality in two cases up for argument next month.

Harris said existing state law, which he shepherded through the General Assembly two years ago and allows gay couples to enter into civil unions, has created a “separate but unequal” system.

Supporters and opponents filling a Capitol committee room waited six hours before testimony. A fiery discussion over legalizing the carrying of concealed weapons consumed lawmakers all afternoon and evening.

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Advocates who testified before the committee included Chicago religious leaders, a lesbian couple and a psychologist.

The Rev. Otis Moss III, senior pastor at Chicago’s Trinity United Church of Christ, said the bill would enhance America’s ideals as a nation and guarantee that all Illinoisans are treated equally.

“We are called to live our faith, not legislate our faith …,” Moss said. “It’s the charge of civil leaders to ensure that everyone is treated equally.”

Advocates also argued that the bill would help eliminate discrimination against children of same-sex couples.

But opponents say the plan steps on people’s religious freedoms. They argue lawmakers don’t have the right to redefine marriage.

Committee members, noting their fatigue after a day of intense debate over guns, cast their votes on the marriage matter after an unusually brief debate on a polarizing issue.

The Senate approved the measure on Valentine’s Day with Democratic support and a lone Republican tally by Champaign Sen. Jason Barickman.

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