The upper house of the US Congress has overwhelmingly backed a bill to slap sanctions on Syria if it fails to address long-standing security issues.
Syria has been accused by the US of aiding terrorists
Senators backed the bill after a similar show of support in the House of Representatives in October.
The bill allows President George W Bush to impose sanctions if Syria is found to be backing terror groups or acquiring weapons of mass destruction.
The Senate amended the bill, meaning it must now go back to the House.
Under the amended bill - passed by 89 votes to four - President George W Bush will have more power to waive the economic and diplomatic sanctions if he deems it in the national interest.
It permits the president to "calibrate US sanctions against Syria in response to positive Syrian behaviour", explained Richard Lugar, chairman of the Senate Foreign Relations Committee.
No senator spoke against the bill, which bans any US trade with Syria in items which could be used in weapons programmes.
It also allows the president to choose at least two other sanctions such as barring US businesses from investing in Syria, restricting travel in the US by Syrian diplomats or banning exports of US products other than food and medicine to Syria.
The BBC's Michael Buchanan reports from Washington that trade between the two countries is paltry - around $150m a year - and Syria receives no US foreign aid.
Our correspondent says that the biggest losers could be American companies who have been recently been contracted by Damascus to explore for oil.
The Bush administration was at one stage reluctant to pursue sanctions against Syria despite Congressional support but it changed its stance after accusing Damascus of failing to curb Palestinian and Lebanese guerrilla groups.
US officials have also voiced concern that foreign militants fighting the US-led coalition in Iraq enter the country from Syrian territory.