SPRINGFIELD – The push to allow same-sex marriages in Illinois got its biggest victory to date Thursday with a historic Valentine’s Day vote in the state Senate, and supporters expressed confidence that within two weeks President Barack Obama’s home state could join nine others that have lifted their gay-marriage bans amid shifting public opinion.

With a 34-21 vote, senators advanced the measure to the House, where it could be a tougher sell even though Democrats also hold a majority there. Gov. Pat Quinn, a Chicago Democrat, has pledged to sign it into law should the House pass it too.

Senate approval was a significant – and at times elusive – step forward for the issue, just two years after legislators approved civil unions. Never had a plan to lift the gay-marriage ban won approval on the floor of either chamber.