WASHINGTON - The Obama administration's nearly yearlong effort to engage Iran has fallen short and new sanctions are needed to press the Iranian leadership to come clean about its suspect nuclear program, Secretary of State Hillary Rodham Clinton said yesterday.

Clinton's pessimistic remarks come as an end-of-year deadline set by President Obama looms for the Iranians to prove that their nuclear intentions are peaceful.

She said the administration had offered Iran a chance to participate in meaningful discussions about its nuclear activities and intentions or face fresh penalties for defiance.

The administration's carrot-and-stick effort, though, has "produced very little," she said, adding that "additional pressure is going to be called for" to get results.

"I don't think anyone can doubt that our outreach has produced very little in terms of any kind of a positive response from the Iranians," she told reporters at a State Department news conference with visiting Spanish Foreign Minister Miguel Moratinos.

Her remarks also came as the House prepares to vote today on legislation that would give the administration authority to punish foreign individuals and companies that sell or ship gasoline to Iran. The bill, the Iran Refined Petroleum Sanctions Act, is expected to pass easily.

Similar legislation is under consideration by the Senate but is unlikely to be adopted before January.

"The second track of our dual-track strategy is to bring the international community together, to stand in a united front against the Iranians and try to impress upon them the importance of changing their actions and decisions concerning their nuclear program," Clinton said.

That won't be easy. Russia and China, both with strong trade ties to Iran, continue to be averse to new sanctions. Just yesterday, international officials said a meeting of five world powers on the issue was canceled at China's request and replaced with a conference call next Tuesday.

Israel sees a threat to its existence from a nuclear-armed Iran and Defense Minister Ehud Barak said in Vienna, Austria, yesterday that military strikes remain an option.

As Obama's deadline nears, the administration is also preparing to press the United Nations, individual countries, and blocs of nations, such as the European Union, to adopt a range of new sanctions.

Iran is already under three sets of penalties from the U.N. Security Council as well as unilateral sanctions from numerous states.

The administration's suggested package of sanctions includes travel restrictions and asset freezes on specific Iranian individuals and entities along with measures targeting the trade and commerce; insurance and reinsurance; banking, energy, and shipping sectors, according to officials familiar with it.

The push toward new sanctions has picked up steam among the Western allies in recent weeks as Iran has bolstered its defiance of attempts to get it to prove its nuclear program is civilian, as it says, and not a covert attempt to develop atomic weapons, as the allies fear.

Iran balked after agreeing in principle to a program under which it would ship uranium abroad to be enriched for use in a civilian reactor - thus preventing it from enriching the uranium to levels suitable for weapons.

Instead, Iranian officials announced plans to build more enrichment facilities. That followed the disclosure in September of a previously secret facility near the city of Qom.