"Before weighing the use of military force, Congress must fully debate and consider the facts and every alternative, as well as determine how best to end the violence and protect civilians," they wrote.

"While we understand that as Commander in Chief you have a constitutional obligation to protect our national interests from direct attack, Congress has the constitutional obligation and power to approve military force, even if the United States or its direct interests (such as its embassies) have not been attacked or threatened with an attack," it added. "As such, we strongly urge you to seek an affirmative decision of Congress prior to committing any U.S. military engagement to this complex crisis."

The letter follows other letters from Republicans and Democrats calling on Obama to seek congressional approval. More than 100 members warned earlier in the week that the War Powers Resolution does not allow Obama to bomb Syria given that Syria poses no immediate threat to the United States.

The Democratic letter said that while human rights violations are "horrific," they "should not draw us into an unwise war."

Speaker John BoehnerJohn Andrew BoehnerSome doubt McCarthy or Scalise will ever lead House GOP Lobbying World McCarthy courts conservatives in Speaker's bid MORE (R-Ohio) has called on Obama to answer more than a dozen questions about his strategy for Syria before any attack begins, and has said Obama needs to make a public case to the American people before any actions are taken.