Protesters march on Wilshire Blvd. during an anti-war rally in Los Angeles, California September 7, 2013. [Photo/Agencies]

WASHINGTON — The White House asserted Sunday that a "common-sense test" dictates the Syrian government is responsible for a chemical weapons attack that President Barack Obama says demands a US military response. But Obama's top aide says the administration lacks "irrefutable, beyond-a-reasonable-doubt evidence" that skeptical Americans, including lawmakers who will start voting on military action this week, are seeking.

"This is not a court of law. And intelligence does not work that way," White House chief of staff Denis McDonough said during his five-network public relations blitz Sunday to build support for limited strikes against Syrian President Bashar Assad.

"The common-sense test says he is responsible for this. He should be held to account," McDonough said of the Syrian leader who for two years has resisted calls from inside and outside his country to step down.

Asked in another interview about doubt, McDonough was direct: "No question in my mind."

The US, citing intelligence reports, says the lethal nerve agent sarin was used in an Aug. 21 attack outside Damascus, and that 1,429 people died, including 426 children.

The number is higher than that, said Khalid Saleh, head of the press office at the anti-Assad Syrian Coalition, who was in Washington to lobby lawmakers to authorize the strikes. Some of those involved in the attacks later died in their homes and opposition leaders were weighing releasing a full list of names of the dead.

The Britain-based Syrian Observatory for Human Rights, which collects information from a network of anti-government activists, says it has so far only been able to confirm 502 dead.

The actual tally of those killed by chemical weapons is scant compared to the sum of all killed in the upheaval: more than 100,000, according to the United Nations.

In an interview Sunday, Assad told US journalist Charlie Rose there is not conclusive evidence about who is to blame for the chemical weapons attacks and again suggested the rebels were responsible. From Beirut, Rose described his interview, which is to be released Monday on the CBS morning program that Rose hosts, with the full interview airing later in the day on Rose's PBS program.

Asked about Assad's claims there is no evidence he used the weapons, Secretary of State John Kerry told reporters in London: "The evidence speaks for itself."

At the same time, Obama has planned his own public relations effort. He has scheduled six network interviews on Monday and then a primetime speech to the nation from the White House on Tuesday, the eve of the first votes in Congress.

Sunday night, Obama dropped in on a dinner held by Vice President Joe Biden for Republican senators, including Lindsey Graham of South Carolina, Susan Collins of Maine, Kelly Ayotte of New Hampshire and Bob Corker of Tennessee.

Obama will meet with Senate Democrats Tuesday, a Senate aide said, speaking on condition of anonymity because he was not authorized to publically discuss the meeting before its official announcement.