AMMAN (AFP) - White House hopeful Barack Obama stepped into the maelstrom of the Middle East Tuesday, warning the next US president could not just snap his fingers and make peace, as fresh violence rocked the region.

The Democratic senator's high-risk tour to prove his commander-in-chief mettle touched down in Jordan for one-on-one talks with King Abdullah II, and an onward journey to Israel and a packed presidential-style schedule.

But the region's tensions immediately intruded, as a Palestinian man was shot dead after launching a bulldozer rampage which wounded at least 16 people near Jerusalem's King David Hotel where Obama was to stay.

Obama condemned the attack, saying it was a reminder of what Israelis have to "courageously live with on a daily basis for far too long," and promised to vigorously join the search for Middle East peace if he is elected in November.

The Illinois Senator, who is being advised by ex-president Bill Clinton's former Middle East envoy Dennis Ross, backed the two state solution to the Israeli-Palestinian conflict.

But a day before meeting Israeli and Palestinian leaders, he warned that entrenched positions, divisions among Palestinians and turbulent Israeli politics meant progress could be slow.

"It is a very difficult process. There is a lot of history that exists between those two people. That history is not going to vanish overnight. "So I think it's unrealistic to expect that a US president alone can suddenly snap his fingers and bring about peace in this region."

Obama flew in from Iraq aboard a US military aircraft, and disembarked carrying a helmet and a flak jacket and wearing a wrinkled shirt and heavy duty hiking boots following his stealth visit to Iraq.

While Obama is likely to be greeted as a hero in Europe, there remain questions in the Middle East about his potential policies towards the region.

His view that Jerusalem must remain the undivided capital of Israel sparked fury among Palestinians, who saw it as pre-judging final status talks, while his offer to talk to Iran is likely to face scrutiny in Israel.

King Abdullah, fresh from a trip to the United States, held closed talks with Obama before hosting a formal dinner.

A palace statement said that during the talks King Abdullah had stressed that ending the Israeli occupation of Palestinian land and achieving a just settlement to the Arab-Israeli conflict "tops the priorities of the people of the Middle East."

"The king told Obama that continued American support for a Middle East peace process that leads to a just and comprehensive peace would help foster Arab-US relations and bolster US credibility in the region," the statement added.

In Colorado on Monday, King Abdullah said he would keep any advice to Obama private, but urged a vigorous future US role in peace moves.

"I see us at a crossroads -- a time of danger and challenge, but also, unique opportunities," he said.

Obama's Israel schedule has more in common with a presidential trip than that of a mere candidate.

He will meet Prime Minister Ehud Olmert, President Shimon Peres, Foreign Minister Tzipi Livni, opposition Likud party chief Benjamin Netanyahu and Defence Minister Ehud Barak.

Obama will also pay homage to Holocaust victims at the Yad Vashem Memorial and hold talks with Palestinian president Mahmud Abbas in Ramallah.

The Obama camp again sought to clarify his position on Jerusalem after his comments to the US Jewish lobby in June, which aides later admitted were poorly worded.

"He has repeatedly said that Jerusalem is a final status issue to be negotiated by the parties, that Jerusalem will remain Israel's capital, but it should not again be divided by barbed wire and checkpoints," said one advisor.

After spending two days in Israel, Obama will head to Germany for the symbolic centrepiece of his campaign swing, a major open-air speech in Berlin on US transatlantic relations.

The tour, which also involves stops in France and Britain, is seen as an attempt to prove Obama's credentials as a potential US commander-in-chief -- one of the few areas in opinion polls where he trails McCain.

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