Top U.S. lawmakers from both parties say they will support President Barack Obama in a military intervention against Syria when the issue comes to a vote as early as next week.
U.S. House Speaker John Boehner and House Minority Leader Nancy Pelosi made the comments after a White House meeting with Mr. Obama on Tuesday.
Boehner, leader of the Republican party in the House of Representatives, says the United States has the capability to stop Syrian President Bashar al-Assad and must send a warning to other countries that the use of chemical weapons will not be tolerated.
Nancy Pelosi, who leads Mr. Obama's Democratic Party in the House, said Syria's use of chemical weapons was outside of the "circle of civilized behavior." She said the United States must respond.
The Syrian government has denied chemical weapons use by the military.
Senate Intelligence Committee chairwoman Dianne Feinstein, a Democrat, said she is fully supportive of Mr. Obama's intended action.
Congressman Eliot Engel, the most senior Democrat on the House Foreign Affairs Committee, said he hopes Mr. Obama receives bipartisan support for military action against what Engel called a war crime.
"To turn weapons of mass destruction on your own population is the most despicable thing that anyone can do. If we did not respond, in kind, it would send a message to every despot, every thug, every dictator, every terrorist group in the world that you can commit war crimes and murder your own citizens with impunity and nothing is going to happen. "
Heading into the session, Mr. Obama said he was confident he could work with Congress to get a resolution authorizing military action.
He said he was asking Congress to approve a "proportional, limited" military response that would send a "clear message" to Mr. Assad's regime and any other country interested in "testing international norms."
"We recognize that there are certain weapons that when used can not only end up resulting in grotesque deaths but also can end up being transmitted to non-state actors, can pose a risk to allies and friends of ours, like Israel, like Jordan, like Turkey."
He also said the U.S. had a "broader strategy" that involves upgrading the capabilities of the Syrian opposition.
Later Tuesday, the Senate Foreign Relations Committee convened to hear testimony from Secretary of State John Kerry, Defense Secretary Chuck Hagel and the chairman of the Joint Chiefs of Staff, General Martin Dempsey.
In another development, French President Francois Hollande said he will wait to see if Mr. Obama receives support from Congress before deciding on a French role in any military intervention. France had earlier voiced support for military strikes against the Syrian government.
U.N. Secretary-General Ban Ki-moon says a use of force is only legal when it is in self defense or within the authorization of the U.N. Security Council.
He told reporters on Tuesday that a U.N. inspection team that collected samples, last week, at the site of the suspected chemical attack near Damascus is working around the clock to prepare its information.
Mr. Ban said it was important not to jeopardize the scientific deadlines needed for accuracy.