When the Congress of the United States of America authorizes a military intervention, the result is usually a war. American presidents, even after the passage of the 1973 War Powers Resolution, generally have not sought congressional approval in advance of brief interventions and targeted military strikes. That makes Obama's request for Congress to authorize the use of force in a limited strike against Syria unusual.
But I wonder if there's not also a logic of escalation that comes into play now that Obama has requested Congressional authorization, creating a very real possibility that the result of a formal authorization for use of force will be a more aggressive or protracted intervention than what we'd have seen had the president not sought Congress's buy-in. If Obama had acted alone to order a bombing campaign over Labor Day weekend, that would likely have been the end of it. Outraged liberals and furious isolationist Republicans would have united in criticism of his use of presidential power, rallying forcefully against further intervention in a conflict the vast majority of Americans don't want the U.S. to enter.
Now, however, we are seeing pressure from Republican hawks for the administration to go beyond Obama's rather clinical rationale for intervention -- upholding the international norm against chemical-weapons use that the major norm-setting international institutions, such as the U.N., scarcely seem devoted to any more. Senators like John McCain and Lindsey Graham want the outcome of the congressional process to be a strategic plan for resolving the conflict in Syria and removing Bashar al-Assad from power.