The Bush administration is getting closer to a U.N. Security Council rebuke of Iran, but the latest round of diplomacy shows the United States needs the help of Cold War foe Russia to close the deal.

Russian Foreign Minister Sergey Lavrov is holding multiple meetings with Secretary of State Condoleezza Rice, plus a highly unusual session in the Oval Office with President Bush on Tuesday.

Rice and Lavrov had dinner together Monday evening.

U.S. presidents customarily receive foreign heads of state in the presidential office, but seldom invite a lower-ranking official such as a foreign minister for a meeting there.

Russia is also a key player in the U.S. drive to limit aid to the extremist group Hamas, which has taken control of the Palestinian legislature.

The U.S. desire for Russian help against Hamas is just one of several cards Lavrov holds as the Security Council prepares to take up the case of Iran's disputed nuclear program.

Russia, which has veto power as one of the permanent members of the Security Council, is perhaps Tehran's most important ally and business partner. Russia also has crafted a potential compromise to head off sanctions or other punishment of Iran.

China, which also has veto power on the Security Council, is appealing for further negotiation. "Iran should cooperate closely with the IAEA to settle the nuclear dispute," Foreign Minister Li Zhaoxing said Tuesday in Beijing at a news conference. "There is still room for settlement of the issue in the IAEA."

The United States won a diplomatic coup in February when Russia went along with the U.S.-backed effort to report Iran to the council, but had to agree to a delay of at least a month before the council could take any action. That window is closing without the progress Russia hoped to claim on its proposed nuclear compromise.

It is not clear, however, that Moscow will support a U.S. move for penalties against Iran.

Russian agencies quoted Lavrov as saying Monday that Russia's proposal to move Iran's uranium enrichment program to Russian territory remains on the table, but that Iran must reimpose a moratorium on the enrichment of uranium and agree to new scrutiny by the International Atomic Energy Agency.

"The result of the IAEA session that has begun in Vienna can be satisfactory only if the remaining questions about Iran's past nuclear program are completely answered," Lavrov said in Ottawa, according to the ITAR-Tass news agency.

Rice telephoned Mohamed ElBaradei, head of the IAEA at the agency's Vienna headquarters on Monday to reiterate the U.S. position that Iran "must cease all (uranium) enrichment-related activity," according to State Department spokesman Tom Casey.

Meanwhile, a top State Department official warned that the Security Council will intervene "quite actively" if Iran does not act quickly on the nuclear issue.

The IAEA will reaffirm its stance this week in Vienna, "unless Iran does a dramatic about-face and suspends all of its nuclear activities," Undersecretary of State Nicholas Burns told the Heritage Foundation, a private research group.

He did not say what the United States would ask the Security Council to do. While the Bush administration takes a stern line toward Tehran it is not seeking economic or other penalties immediately, and might not be able to win Russian or other backing for that move in any case.

Russia is something of a wild card, in international efforts to persuade the new Palestinian Hamas leadership to recognize Israel and renounce violence, or suffer a devastating loss of overseas financial backing.

Russian President Vladimir Putin invited Hamas leaders to Moscow last weekend, a move that angered Israel and surprised the United States and Russia's other partners in the so-called Quartet of Mideast negotiators. The United States, European Union and Israel consider Hamas a terrorist organization.

On both Iran and Hamas, the United States needs Russian acquiescence, if not outright support.

That may make it more difficult for the administration to press Lavrov very hard over what Rice recently called a disturbing erosion of democratic guarantees in post-Soviet Russia. U.S. officials insist they will not give Russia a pass.

"There are areas where ... we differ, and we think we can have a frank and candid exchange of views with them on those subjects," State Department spokesman Tom Casey said Monday. "We're certainly going to continue to make clear our concerns about those areas where we do have problems."

Putin, while on good terms personally with Bush, has been criticized for centralizing political power and rolling back democratic gains.