The administration of US President Barack Obama has admitted that it lacks “irrefutable, beyond - a - reasonable - doubt evidence” for its claims that the Syrian government used chemical weapons in an attack last month.The Obama White House has accused the government of Syrian President Bashar al-Assad of using chemical weapons in an attack near capital Damascus on August 21. In an interview with CBS News’ Face the Nation on Sunday, the Syrian President rejected the allegations that he was behind the deadly chemical attack in August. Washington has not provided any conclusive evidence for its claims as Russian Foreign Minister Sergey Lavrov described the information provided to Russia as “some sketches” which contained “no supporting facts.” And now, Obama’s top aide, White House chief of staff Denis McDonough, has said that Washington claims are based on a “common-sense test” not any “irrefutable” evidence. "This is not a court of law. And intelligence does not work that way," said McDonough on Sunday. “The common-sense test says he [President Assad] is responsible for this. He should be held to account.” Meanwhile, key members of the Obama administration are struggling to muster support for the White House’s war plans against Syria both from abroad and from within US public and Congress. Obama’s Secretary of State John Kerry is now in Europe courting Washington’s allies in an all-out push for an attack on Syria. Kerry held talks with Arab League foreign ministers in Paris and is set to travel to London next before returning to Washington on Monday to continue selling the proposed “limited military strikes” plan at home to the growingly skeptical Congress and American public. The White House’s lobbying efforts come as recent polls show a growing opposition to the administration’s war plans amid the US public. A recent Gallup poll has shown that support among Americans for a US military action against Syria is among the lowest for any military intervention in the past two decades. A recent Washington Post-ABC News poll has also shown that nearly 60 percent of Americans are against missile strikes on Syria. Also on Saturday, American antiwar activists gathered in Times Square in New York City and outside the White House in Washington to voice their opposition to another war in the Middle East.