"In my opinion, we have waited long enough for the diplomacy to work. Iran is a festering sore in the world," Democratic Senate Majority Leader Harry Reid told reporters in unusually tough language.
Reid's comments came as the US Congress took a key step towards imposing new sanctions targeting Iran's imports of gasoline and other refined petroleum products to force the Islamic republic to halt its suspect nuclear program.
The House of Representatives voted 403-11 to appoint "conferees" to huddle with their Senate counterparts and meld the two chambers' rival versions of sanctions legislation into one compromise bill for passage within weeks.
"As they get it out, I will move everything within my power to move it to the floor. The Middle East is unstable. This will help stabilize it," Reid said after the vote, which urges the lawmakers complete their work by May 28.
Because of a lack of domestic refining capacity, oil-rich Iran is dependent on gasoline imports to meet about 40 percent of domestic consumption.
The House overwhelmingly passed its version of the bill in December, followed by the Senate in January, but the two bills diverge on several critical points and face some resistance from the US State Department.
President Barack Obama's administration has pressed lawmakers to hold off on US sanctions until it can try to win new UN sanctions against the Islamic republic, which denies Western charges it seeks a nuclear arsenal.
"This may be our last chance to apply pressure on Iran before it is too late," said Representative Ileana Ros-Lehtinen, who charged Iran was sprinting "to the nuclear finish line."
Ros-Lehtinen, the top Republican on the House Foreign Affairs Committee, complained that China and Russia were resisting UN action on Tehran, and warned: "The clock is ticking, the centrifuges in Iran are spinning."
Tehran has resisted previous UN sanctions aimed at forcing it to freeze its uranium enrichment, which can be a critical step towards making a nuclear bomb.
Top US military officials told lawmakers last week that Iran could enrich enough weapons-grade uranium for one bomb within a year, and could overcome other obstacles and assemble one weapon within 3-5 years.
"The world faces no security threat greater than the prospect of a nuclear Iran," said Democratic Representative Howard Berman, the panel's top Democrat. "We must make certain that the prospect never becomes a reality."
