Lawmakers in favor of same-sex "marriage" always speak of such legislation as "the right thing to do" and yet they also recognize that passing such a bill will likely harm their re-election efforts:
The key hurdle is timing. Lawmakers will start filing re-election paperwork at the end of November, so casting a vote for gay marriage now would leave a month or so for challengers opposed to it to gather enough signatures to get on the March primary election ballot.This is precisely why the bill did not muster enough votes in the last session (and why the General Assembly passed the so-called Religious Freedom Protect and Civil Union Act in the "lame duck" session when their re-elections were not at risk). It simply shows that the legislators are uncertain as to the "right thing" to do because, one might argue, deep down they fully understand the difficulties this bill places on religious liberty.
N.B.: If you're in Illinois, be sure to attend the Defend Marriage Lobby Day and speak with your elected representatives. Tell you Senator to vote "No" on SB10.