The White House narrowed its strategy Sunday on convincing Capitol Hill that the United States should launch a military strike on Syria, asking why wouldn't lawmakers agree to punish the use of nerve gas on children and others when the evidence is indisputable and suggesting such a move is as much about sending a message to Iran as it is about punishing the Syrian government.
"Not a person is refuting the evidence," White House Chief of Staff Denis McDonough told "Fox News Sunday." "The question now before Congress is … should there be consequences?"
McDonough was scheduled to appear Sunday on all of the major morning talk shows to convince Capitol Hill and the American public that the U.S. should launch a punitive strike against Syrian President Bashar Assad, who the administration believes ordered an Aug. 21 chemical weapons attack that killed more than 1,400 people, including hundreds of women and children.
McDonough's efforts are part of an all-out administration effort to convince Congress to support a strike, which will be highlighted by President Obama's speech Tuesday.
The president said last weekend that he decided that the U.S. should respond with a "limited" and "targeted" strike, but ask for congressional approval -- as members return Monday from summer recess.
"This is a very important week," said McDonough, who said several times Sunday that Iran, which is trying to develop a nuclear weapon, is watching to see what the U.S. will do.
"This is an opportunity to be bold with the Iranians," he said on NBC's "Meet the Press."
The White House is making a big push to rally members of Congress and the American public behind President Barack Obama's plan for a U.S. military strike against Syria.
Also ahead of the president's national address Tuesday, Vice President Joe Biden plans to host a dinner Sunday night for a group of Senate Republicans. And lawmakers should expect more phone calls from top officials.
Recent opinion surveys show intense American skepticism about military intervention in Syria, even among those who believe Syria's government used chemical weapons on its people.
On Wednesday, the first showdown Senate vote is likely over a resolution authorizing the "limited and specified use" of U.S. armed forces against Syria for no more than 90 days and barring American ground troops from combat. A final vote is expected at week's end.
A House vote appears likely during the week of Sept. 16.
A survey by The Associated Press shows that House members who are staking out positions are either opposed to or leaning against Obama's plan for a military strike by more than a 6-1 margin. The Senate is more evenly divided ahead of its vote.
Nearly half of the 433-member House and a third of the 100-member Senate remain undecided.
Complicating the effort in the Senate is the possibility that a three-fifths majority may be required. Republican Sen. Rand Paul of Kentucky says he is going to filibuster.
Still, Sen. Harry Reid, the Democratic leader, has predicted, "I think we're going to get 60 votes."
Rand told Fox News on Sunday that a filibuster is only a temporary stop.
A bipartisan, classified briefing for Congress is set for Monday.
McDonough plans to meet Tuesday with the House Democratic Caucus, whose support could be crucial as Obama faces opposition from House Republicans.
Obama's national security adviser, Susan Rice, plans to discuss Syria in a speech Monday at the New America Foundation.
At least 150 people picketed outside the White House on Saturday to oppose any military action against Syria. Demonstrations also took place in New York City, Boston and Indianapolis, and in Louisiana and Michigan.
Also Saturday, a U.S. official released a DVD compilation of videos showing victims of the Aug. 21 attack. The DVD was shown to senators during a classified briefing.
The Associated Press contributed to this report.