It's the one major Muslim nation not on the invitation list for the upcoming U.S.-convened peace parley, yet it will haunt every discussion.

Iran's importance to the Israeli-Palestinian peace conference in Annapolis, Md., was underscored by how the subject of Iran seeped into two recent Washington think-tank sessions on the talks -- one casting the renewed peace push as a means toward limiting Iran's influence, the other framing it as a gift to the Islamic Republic's plan for regional domination.

On Nov. 20, the International Crisis Group and the liberal New America Foundation held a session promoting a letter sent to U.S. President George W. Bush and his secretary of state, Condoleezza Rice, that calls on the international community to play an interventionist role in the peace process.

Top former Cabinet-level officials signed the letter, which cast the initiative against the backdrop of broader instability in the region.

"The Middle East remains mired in its worst crisis in years and a positive outcome of the conference could play a critical role in stemming the rising tide of instability and violence," it said. "Because failure risks devastating consequences in the region and beyond, it is critically important that the conference succeed."

Speaking at the session Ghaith al-Omari, a former Palestinian Authority negotiator who is now affiliated with the American Task Force on Palestine, drew a direct line between the Israeli-Palestinian impasse and the ability of the Iranians to promote instability.

"Every time you want to raise emotions, you wave the Palestinian flag," al-Omari said, describing what he said was the strategy favored by Iranian President Mahmoud Ahmadinejad.

A couple of hours later and a few blocks away at an Israel Project luncheon, David Wurmser, until earlier this year U.S. Vice President Dick Cheney's top Middle East adviser, also assigned Iran a critical role in the process -- but drew an opposite conclusion about the usefulness of the renewed peace talks.

Wurmser predicted the Iranians would depict any Israeli concession as the fruit of terrorism carried out by its proxies and allies.

"We were the ones to create the terror to force the Israelis to cede land" is how Iran would depict the outcome, said Wurmser, who now runs a crisis management consultancy firm.

Iran's suspected drive toward a nuclear weapons capability is helping to push the peace process forward. Bush and Rice have said the conference and a proposed $20 billion weapons sale to Saudi Arabia will help create a united regional front against Iranian hegemony.

The 40 invitees to the conference include all the Arab and major Muslim states except Iran. Getting the Saudis on board, in particular, was seen as critical; Bush phoned in a personal appeal to King Abdullah on Tuesday, and on Friday, Prince Saud al-Faisal, the Saudi foreign minister, confirmed he would attend.

Another invitee, Syria, is seen as a means to limiting Iranian influence in the region. Deputy Syrian Foreign Minister Faysal Mekdad will attend the conference, a Damascus official said Sunday.

Prior to the announcement, the reasoning was that if Syria joins the talks, that could lead to an Israeli-Syrian deal and the end to Syria acting as an intermediary between Iran and its Lebanese proxy, Hezbollah. Without Syria, Hezbollah is much less likely to engage in another war of the kind it did in the summer of 2006 against Israel.

Bush is to meet Israeli Prime Minister Ehud Olmert and Palestinian Authority President Mahmoud Abbas in the White House on Monday. The parties will dine at the State Department, where Bush will deliver introductory remarks.

On Tuesday, the parties will meet in Annapolis, where Bush again will open the session. After speeches by the principals, the conference will break into three sessions: one on economic support for the Palestinians, one on political support for the process and one simply titled "Comprehensive Peace."

That session may be the key to edging the Saudis and other Arab nations toward peace with Israel, a critical element for Olmert in making the case for concessions to the Palestinians to a skeptical Israeli public.

For now the Saudis appear to prefer informal alliances as a means of heading off Iran, but pro-Israel groups in the United States are saying Israel needs formal relations with the Saudis if the process is to work.

"Arab leaders should also attend the upcoming Annapolis meeting and provide Abbas with the political backing he will need to fight terrorism and make the tough compromises necessary to reach an agreement with Israel," said Howard Kohr, the executive director of the American Israel Public Affairs Committee, in an opinion piece distributed by AIPAC via e-mail. "To facilitate Arab-Israeli peace efforts, the Arab states must also begin to prepare their own people by recognizing Israel's right to exist, ending their economic boycott of the Jewish state and supporting peace."

In another opinion piece Abraham Foxman, the national director of the Anti-Defamation League, said the time was right for amping up Arab rapprochement with Israel.

"The Arab world, in a distressed state over the growing regional power of Iran and its allies, Hezbollah and Hamas, is more open to supporting an Israeli-Palestinian agreement," Foxman said.

Wurmser said such rapprochement could backfire. Iran would depict it as "the Saudis and others march off to Annapolis in order to give up the banner of Islam, in order to save their regimes."

That option should be headed off by bringing in the Iranians, even indirectly, advised Robert Malley, the former Clinton administration Middle East negotiator. Malley attended the session organized by the International Crisis Group and the New America Foundation.

"You don't want to do this in an environment where you’re excluding nations" that can sabotage the process, said Malley, now director of Middle East programs at the International Crisis Group.