US president Barack Obama faces a tough week of pressing domestic lawmakers to back military action against Syria as his administration made fresh claims about the Assad regime's use of chemical weapons.
In a surprise decision on Saturday, Mr Obama delayed "limited" military intervention against Syria's government over the gassing of 1,429 people in last month's attack on a rebel-held suburb of Damascus, saying the US should strike against Syria but he would seek the approval of Congress.
In a round of appearances on political talk-shows yesterday, secretary of state John Kerry stressed the Obama administration could still choose to take military action even without congressional approval but he said the backing of US lawmakers would give any military action greater credibility.
Chemical weapons
"We don't contemplate that the Congress is going to vote no," Mr Kerry said.
Congress had a duty to act to uphold international norms against chemical weapons, he added.
Mr Kerry made new claims that Assad's forces used deadly sarin gas in the August 21st attacks, saying blood and hair samples taken from emergency workers tested positive for the nerve agent. Referring to the new evidence obtained in the previous 24 hours as a further reason to approve military action, Mr Kerry said the case against Assad was "building" and growing stronger "by the day".
Gamble
Mr Obama's move to seek congressional approval is seen as a gamble because of the strong opposition to him on Capitol Hill. The move delays any US action until Monday week at the earliest when Congress returns from its summer break.
The timing may be further complicated as UN chemical experts will take up to three weeks to analyse evidence collected at the scene of the chemical attack.
