WASHINGTON — Senator Obama is in Jerusalem today for perhaps the most challenging test yet of his presidential tryout on the world stage.

Not only has Israel’s ruling party just agreed to primaries that will result in new leadership for the Jewish state by mid-September, but relations between the outgoing Olmert government and the Bush administration are at their most strained, with the State Department charting new policy on Iran and negotiations with the Palestinian Arabs.

Complicating matters, Mr. Obama will be meeting with Israeli and Palestinian Arab leaders as the negotiations the White House hopes will result in a Palestinian state are breaking down. President Abbas condemned a bulldozer attack yesterday that injured five people less than 200 yards from the King David Hotel, where the Illinois senator’s entourage is staying.

Mr. Obama also condemned the attack. Before leaving for Tel Aviv yesterday, he told reporters in Amman, Jordan, that he was committed to furthering the Arab-Israeli negotiations. “What I think can change is the ability of the United States government and a United States president to be actively engaged with the peace process and to be concerned and recognize the legitimate difficulties that the Palestinian people are experiencing right now,” he said.

When he arrived in Tel Aviv, however, the presumptive Democratic presidential nominee said he could not “snap his fingers” and create peace between the parties.

Mr. Obama will meet today with Prime Minister Olmert, who agreed this week to stand down when his party, Kadima, holds primary elections on September 18 to replace him. His likely successor will be Foreign Minister Tzipi Livni.

The senator also will meet with the defense minister and head of the Labor Party, Ehud Barak, who as prime minister tried and failed to reach a final status peace accord with the then Palestinian Arab leader, Yasser Arafat. A third meeting is scheduled with the Likud prime minister Mr. Barak unseated in 1999, Benjamin Netanyahu.

All of the Israeli leaders will be seeking to show they are comfortable with an Obama presidency, a former American ambassador to Israel and the director of the Saban Center for Middle East Policy, Martin Indyk, said. “Israeli leaders will be keen to seek out a feeling for two things,” he said. “Does he understand the danger Iran poses? Two, when the chips are down, will he be in Israel’s corner?”

Mr. Indyk added that it is in every Israeli politician’s interest to show that they could manage a relationship with the man who could be the next president, or “the American political rock star,” as he called Mr. Obama. (Mr. Indyk has served as an independent adviser to the Obama campaign.)

For some, Mr. Obama dispelled concerns about his position on Israel when he appeared last month before the American Israel Public Affairs Committee’s annual conference and committed his support for defensible Israeli borders and said he would not allow Iran to build a nuclear weapon.

Mr. Obama also told the conference he favored an “undivided Jerusalem,” which he defined the next day as an Israeli capital that was not divided by a physical barrier but would not preclude a binational city that served as capital both of Israel and a Palestinian Arab state.

A senior foreign policy analyst at the Jerusalem Center for Public Affairs, Dan Diker, said Mr. Obama was coming to Israel as the country was in a “precarious political situation.” But he added: “Obama has already positioned himself close to the Israeli center on defensible borders, condemning the bulldozer terrorist attack when he was in Amman, and he clearly has backed Israel’s right to defend itself. He is acutely aware of the threat Iran represents.”