Dennis Ross, a longtime Middle East expert, has emerged as a crucial, behind-the-scenes conduit between the White House and the Israeli government, working closely with Prime Minister Binyamin Netanyahu's private attorney - and also Defense Minister Ehud Barak - to discreetly smooth out differences and disputes between the two governments.

Ross's role, described by officials and other sources close to the process, is highly sensitive because it might be seen as undercutting the mission of George J. Mitchell, President Obama's special envoy for Middle East peace. Virtually no one interviewed would agree to be quoted by name because of such concerns.

Mitchell also deals directly with the lawyer, Yitzak Molho. But it was Ross - a senior director for Middle East policy on the White House staff - who primarily worked with Molho and Barak on a package of incentives that the Obama administration is offering Netanyahu to extend a settlement moratorium by 60 days to keep nascent peace talks with the Palestinians on track.

The White House referred questions to the State Department. "Dennis Ross' important role in this effort is actually well known and greatly appreciated," State Department spokesman P. J. Crowley said in a statement. "Working with George Mitchell and at the direction of [Secretary of State Hillary Rodham Clinton], he is encouraging the parties to continue negotiations towards an agreement that leads to a two-state solution."

Sources in both the United States and Israel said that Ross has provided an element that had been missing from the bilateral relationship, which has been rocky since Obama took office.

Israeli officials have long preferred to bypass the State Department and peace envoys, and deal directly with a senior official in the White House. Former officials from Bill Clinton's and George W. Bush's administrations said the Israelis think that the White House ultimately makes foreign policy and are convinced that the State Department is too pro-Arab.

In the Bush administration, national security adviser Condoleezza Rice worked closely with Dov Weissglas, the chief of staff for Prime Minister Ariel Sharon, in effect negotiating Israel's withdrawal from the Gaza Strip. In Bush's second term, national security adviser Stephen J. Hadley dealt directly with Yoram Turbowicz, the chief of staff for Prime Minister Ehud Olmert - often to field complaints about what Rice was doing in her new role as secretary of state.

Netanyahu "was looking for such a channel at first and couldn't find one," a person close to the administration said.

Ross's role became more pronounced after Obama shifted course this year and decided to improve his relationship with Netanyahu.

"Very few players are involved," said an Israeli official, speaking on condition of anonymity. "The prime minister has said it is crucial that we do this in a discreet and quiet fashion."

Ross knows both Molho and Barak well from his central role in the Clinton administration as Middle East peace negotiator. In his memoir, "The Missing Peace," Ross described Molho, a lifelong friend of Netanyahu's, as "the only person Bibi trusted completely" and "probably the only one around Bibi who could tell him what he did not want to hear." During Netanyahu's first turn as prime minister, in the 1990s, Molho initiated contacts with Yasser Arafat when he was the Palestinian leader.

Barak, meanwhile, has emerged as a de facto foreign minister for Israel because Avigdor Lieberman, who holds the post, is a hard-liner whose views are objectionable to U.S. officials. "Barak is someone they know and trust, the go-to person for the United States," said another person close to the administration. Barak, however, is not a close associate of Netanyahu's and, in fact, is a political rival who heads the Labor Party.

Ross originally joined the Obama administration as a senior adviser to Clinton on Iran policy. But within months - and especially after a difficult conversation with Saudi King Abdullah during a trip to Riyadh in June 2009 - Obama decided he needed Ross's expertise on the Middle East inside the White House.

Very quickly, one source said, Ross renewed his contacts with Molho. "It was high risk for Dennis, because he was, in effect, subverting Mitchell and Clinton," the source said. Tensions between the two countries, however, were too high for the Ross-Molho channel to be effective.

Then, the U.S.-Israeli relationship nearly came to a breaking point in March over a perceived snub of Vice President Biden during a trip to Israel. The very public disagreement - Clinton called Netanyahu to publicly berate him - was followed by an administration assessment that temperatures needed to be cooled down.

The administration reacted calmly in June to the deadly Israeli attack on a flotilla of ships headed to Gaza, and then Obama warmly welcomed Netanyahu at a White House meeting in July.

"Once the relationship was repaired, it was much easier for this channel to flourish," the source said.