When the United Nations' 63rd General Assembly session opens on September 23, President Bush will certainly be there for the United States. Mahmoud Ahmadinejad is scheduled to speak for Iran. And leading the Israeli delegation? It's a mystery. The timing of next month's Kadima primary - a week before the annual UN powwow - has created a perfect storm for Israel's delegation, which was supposed to have been led by Prime Minister Ehud Olmert. President Shimon Peres would be a logical stand-in, but he may be required in Israel to oversee the formation of a new government after the September 17 primary, when Olmert plans to step down. Instead, leadership candidate Tzipi Livni has given a tentative RSVP in her capacity as foreign minister, and is scheduled to give the delegation's 15-minute floor speech on September 29. Yet diplomatic sources tell The Jerusalem Post they aren't scheduling any meetings for Livni just yet: If a new government is formed immediately after the September 17 primary, the winner may be eligible to appear in New York the following week, with other heads of state. If the campaign goes to a September 25 runoff election, then Olmert or Peres may wind up making the trip at the last minute. "It's not a question of whether whoever goes is really representing Israel, it's a question of how effective they can be if the domestic political contest in Israel is still an open question," said Tamara Cofman Wittes, a senior fellow at the Saban Center for Middle East Policy at the Brookings Institute in Washington. "They have to fill in the gaps, and there's no real way they can." The situation is another example of domestic political volatility impairing Israel's ability to corral international support, Wittes said. This year's General Assembly, while less high-profile than others in recent years, nonetheless comes as fragile coalitions are shifting in the wake of Russia's invasion of Georgia. "This General Assembly is of particular importance to Israel because of the confluence of the Russian and the Iranian issues," said Michael Oren, a visiting professor at Georgetown University who has advised Israel's UN delegation in the past. "This is really the last chance to galvanize any united Western front against Iran." While the uncertainty over who will be head of state may rob Israel of the valuable opportunity to make a public statement to the world's leaders, the greater cost may be in the lost opportunity for face-to-face diplomacy at the Waldorf-Astoria Hotel: As much as it is a forum for political theater, the General Assembly is also at its heart a very specialized sort of trade convention. "The kind of one-stop shopping that's possible during a General Assembly is important," said Ruth Wedgwood, a professor of international law and diplomacy at the School of Advanced International Studies at Johns Hopkins University. "It's important just being there." The Israeli mission to the UN is in a period of unaccustomed flux following the departure of former UN ambassador Dan Gillerman in July, after six years in the post. His replacement, Gabriela Shalev, hasn't yet arrived in New York. UN protocol experts said it's not uncommon for countries to make last-minute changes in their representation lists, or in some cases to miss the General Assembly altogether: Delegates from newly-admitted Burundi missed the plenary session altogether in 1962 because of airline scheduling problems. "People get sick, people miss their plane," said Margaret Kelley, director of the General Assembly. "We just upgrade or downgrade your representation accordingly."