The Constitution of the United States of America leaves the authority to declare war to Congress, NOT the President.
The War Powers Resolution of 1973 (50 U.S.C. 1541-1548) is a federal law intended to check the president's power to commit the United States to an armed conflict without the consent of Congress. The President can only send U.S. armed forces into action abroad only by declaration of war by Congress, "statutory authorization," or in case of "a national emergency created by attack upon the United States, its territories or possessions.
Congress is elected to represent the people.
We the people say: No war with Syria!