Other questions: Is the credibility of Congress on the line and not Obama's? There have been other chemical attacks in recent history, "Does the US take unilateral action to punish governments and countries that use chemical weapons? The UN says the US needs their approval to carry out a military strike against Syria. Does it?
The U.S. does not NEED the approval of the U.N., ever. We are a sovereign nation. We make our own decisions. If the U.N. disagrees with our decision, they can use U.N. forces to try to stop us. We are not subject to their decisions.
The credibility of Congress is on the line because Obama put the decision before them to consider and make. So their previous resolutions on chemical weapons are relevant. Obama did draw a line.
With that said, I don’t want to spill American blood in a Syrian civil war. I don’t want to support Assad. I don’t want to support Al Qaeda.