A new television advertisement that urges Congress to oppose US military strikes against Syria underscores the difficulty President Barack Obama is having in getting war-weary liberals to support him. The 30-second ad by the liberal activist group MoveOn.org says the US did not set out to spend eight years at war in Iraq and a decade in Afghanistan, and predicts the same thing will happen if Congress approves Obama's desired military action. MoveOn was one of Obama's biggest campaign supporters. But Anna Galland, its executive director, said the organisation was following the will of its members. A recent 24-hour poll of MoveOn's members revealed more than 70 per cent are against military strikes. Recent surveys also show wider public opinion running against US intervention. The ad, titled "Not Again", concludes by telling Congress: "Don't lead us down this road again." Viewers are given a phone number and urged to call Congress to voice opposition. The group is spending tens of thousands of dollars to air the commercial. Galland said the group "will stand closely" with Obama on other issues, such as the implementation of his health care law. But on Syria, "we had a very clear mandate from our members to go out strongly on this," she said.