The House voted overwhelmingly to implement new sanctions against Iran in retaliation for its saber-rattling over building a nuclear weapons arsenal.
By a 412-12 vote, lawmakers approved legislation that would penalize foreign companies that sell oil to Iran or help the country with its oil-producing capacity. While Iran is a major crude oil producer, its lack of ability to produce enough gasoline and other refined petroleum products is a major economic vulnerability.
With no Senate action on the legislation expected this year, the House vote was for the time being mainly a warning that the United States is ready to act on its own if the Tehran government doesn't respond to current international efforts to prevent Iran from becoming a nuclear power.
Some lawmakers who voted against the bill worried such economic consequences could harm impoverished Iranians.
Deputy Secretary of State James Steinberg, in a letter to the Senate Foreign Relations Committee last week, said the Obama administration was "entering a critical period of intense diplomacy to impose significant international pressure on Iran." Sanctions legislation "might weaken rather than strengthen international unity and support for our efforts," Steinberg's letter said.
House Foreign Affairs Committee Chairman Howard Berman, D-Calif., said Iran has had ample time to respond to President Obama's efforts at engagement. "President Obama has offered Iran an outstretched hand, but regrettably, Iran has not unclenched its fist."
Hitting Iran in one of its weakest areas could be "the last best hope for diplomatically ending Iran's nuclear weapons program," said Rep. Mark Kirk, R-Ill.
U.S. officials say Iran has already stockpiled enough uranium to produce one nuclear weapon, said Rep. Ileana Ros-Lehtinen of Florida, top Republican on the Foreign Affairs Committee. International diplomacy has proved to be a mirage, she said. "we must use the limited time remaining to impose sanctions so painful that they should threaten the Iranian regime's survival."
Rep. Dennis Kucinich, D-Ohio, a leading critic of the bill, said it would antagonize the many Iranian people who oppose the Tehran government of President Mahmoud Ahmadinejad. "We're telling the Iranian people, 'we have feelings of friendship for you. we like you so much, but we're going to cut off your home heating oil."'
"This will unify the Iranian people against us," said Rep. Ron Paul, R-Texas.
U.S. petroleum exports to Iran are already banned under past sanctions. But the National Foreign Trade Council and its affiliate, USA Engage, expressed concern that a U.S. company that has business dealings with a foreign firm involved in Iran's energy sector could face sanctions.
Also on Tuesday, the State Department said it planned to waive provisions of existing sanctions against Iran to allow Iranians to download free, mass-market software used in e-mail, instant messaging and social networking.
The department said sanctions "are having an unintended chilling effect on the ability of companies such as Microsoft and Google to continue providing essential communications tools to ordinary Iranians."
Senate Armed Services Committee Chairman Carl Levin, D-Mich., welcomed the move: "Much of what we know about the regime's repression has come from firsthand accounts by Iranian citizens, distributed via Internet tools such as YouTube and Twitter," he said.
Fox News' Chad Pergram and The Associated Press contributed to this report.