CHICAGO – Building on the momentum of President Barack Obama's recent support of gay marriage, two major civil rights groups in his home state filed lawsuits Wednesday in hopes of legalizing same-sex marriage in Illinois.

The two lawsuits — brought by the American Civil Liberties Union of Illinois and the New York-based Lambda Legal — represent 25 couples statewide. Both challenge a state law that defines marriage as between a man and woman, arguing that the Illinois Constitution guarantees the right for same-sex couples to marry under due process and equality clauses.

"It's time for Illinois to recognize the love and commitment of these couples," said John Knight, director of the Lesbian, Gay, Bisexual, Transgender Project of the ACLU of Illinois. "We've waited long enough."