Chants of "One man! One woman!" filled the Illinois Capitol building on Wednesday as opponents of gay marriage rallied to protest a measure that would legalize same-sex unions in the state.
The day before, supporters converged on the same location in Springfield, calling for Illinois to be the 15th state to legalize same-sex marriage.
Illinois, a place President Barack Obama calls home, is one of a handful of states with a Democratic legislature and governor that had been targeted by gay rights activists to approve same-sex marriage this year.
Fourteen states and the District of Columbia recognize gay marriage, with New Jersey the latest to allow it earlier this week. Obama has urged the Illinois state legislature to pass it.
The Illinois state Senate voted in favor on Valentine's Day 2013, but the full state House of Representatives, which has a large Democratic majority, did not consider the bill because of uncertainty over whether it had the votes to pass.
The bill did not come up for a vote in the House before it adjourned on Wednesday until November 5.
Civil unions are legal for gay and lesbian couples in Illinois but that does not guarantee federal benefits to gay partners. Social security payments are limited to same-sex couples living in states which have legalized gay nuptials.
The "Defend Marriage Lobby Day" rally opposed to same-sex marriage on Wednesday drew an estimated 2,500 people, according to Secretary of State Capitol Police. They had put the size of Tuesday's crowd supporting gay marriage at about 3,000.
A large wooden cross with "God abhors civil unions", written in white paint, was propped against a statue of Abraham Lincoln in front of the Capitol, where a rainbow flag representing gay rights had been draped across his shoulders on Tuesday.
"We are here today to send a clear message to our state lawmakers that marriage should not be redefined and undermined, but should rather be promoted and protected," said David Smith, director of the Illinois Family Institute, coordinators of the rally against same-sex marriage.
A poll of 600 voters - commissioned last week by Equality Illinois, which supports gay rights - found that 52 percent of likely Illinois voters say they would support a law legalizing gay marriage, while 40 percent would oppose it.
But the leadership of the Illinois Catholic church, as well as some African-American Christian ministers are strongly opposed and have endorsed ads in key Illinois electoral districts.
On Tuesday, Springfield Catholic Bishop Thomas J. Paprocki barred from the local cathedral anyone praying for same-sex marriage, calling it blasphemous.
(Reporting By Lisa Maria Garza; editing by Gunna Dickson)