When Rand Paul was asked "Can you point to something" that would have forced Obama to reconsider his position of ordering the strikes and instead go to congress first, he said maybe it was the 80% of the public that have been telling all their representatives that they want congress to vote on this at 0:58 seconds in this video:
Like I was saying in the OP this could be all for show, I'm certain some that signed the letter and spoke out did it to score political points never thinking it would actually go to a vote, but that doesn't really matter now. What matters is that it will be going to congress and this vote may very well make or break political careers as congressman will now need to go on the record and cast a vote on the issue. If public opinion continues to be high that we should stay out of the war in Syria this could very well have an impact on the 2014 and 2016 races. Regardless of how these people may have tried to play both sides this has now backfired on those thinking in that way because they will now be forced to choose a side, and there is a very good chance this whole thing maybe stopped in the House, versus the direction we were headed before which was left to Obama's prerogative.