That number shows that, as in Congress itself, a substantial number who would require congressional approval are surely Republicans who just don't think this president should ever have the authority to do anything on his own, but many are Democrats who have less cynical reasons (since the vast majority of reasons are less cynical than the Republican one).
On the question of whether the US should take military action, separate from the question of congressional approval, the numbers vary depending on what's proposed. Asked "Do you think the United States should take military action against the Syrian government in response to the use of chemical weapons or not," 42 percent are in favor while 50 percent are opposed. But when the military action is limited to "air strikes using cruise missiles launched from U.S. naval ships that were meant to destroy military units and infrastructure that have been used to carry out chemical attacks," the numbers basically reverse: 50 percent are in favor while 44 percent are opposed. Still, in both cases support is weaker than the 58 percent support for the statement that "The use of chemical weapons by any country is a 'red line,' that is an action that would require a significant U.S. response, including the possibility of military action."
With the British Parliament's rejection of military intervention and US public opinion in favor of requiring congressional approval, Obama stands the risk of being very isolated if he decides to take military action without going to Congress first.