The House of Representatives voted Tuesday to impose new economic sanctions against Iran, as the US as lawmakers expressed doubt about the Islamic Republic's willingness to respond to diplomatic efforts to curtail its purported nuclear arms program. A senior Iranian oil official, however, said on Wednesday that the move by US lawmakers would not cause any problems because Teheran had many suppliers, according to Reuters. "They cannot succeed," Hojjatollah Ghanimifard, senior vice president of investment affairs at the state National Iranian Oil Company told Reuters. The US legislation, approved 412-12, would end access to US markets for foreign companies that sell refined petroleum products to Iran or help that country develop its petroleum 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 primarily a warning that the United States is ready to act on its own if the Teheran government does not respond to current international efforts to prevent Iran from becoming a nuclear power. The bill drew opposition from lawmakers who said it would mainly cause hardship among poor and middle-class Iranians. Deputy Secretary of State James Steinberg, in a letter to the Senate Foreign Relations Committee last week, said President Barack Obama's 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, a member of Obama's Democratic Party, said Iran has had ample time to respond to 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 Republican Rep. Mark Kirk. US officials say Iran already has stockpiled enough uranium to produce one nuclear weapon, said Rep. Ileana Ros-Lehtinen, 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." Democratic Rep. Dennis Kucinich, a leading critic of the bill, said it would antagonize the many Iranian people who oppose the Teheran 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, a Republican. US petroleum exports to Iran already are banned under existing sanctions. But the National Foreign Trade Council and its affiliate, USA Engage, expressed misgivings that a US 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, a Democrat, 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.