US President George W Bush will leave shortly for the Middle East in a bid to further Israeli-Palestinian peace efforts.

He will also try to rally Arab opposition to Iran, especially in light of the recent clash between American and Iranian vessels in the Strait of Hormuz.

It will be Mr Bush's first presidential visit to Israel and the West Bank.

It has led to claims that his underlying motive for the trip is to ensure his presidency is not defined entirely by the unpopular war in Iraq.

The chances of a peace deal seem slim, as Mr Bush has been vague about the trip's objectives and has not announced any plans to hold a three-way meeting with Israeli and Palestinian leaders.

However, aides insist Mr Bush will encourage Israelis and Palestinians to move talks forward after they pledged to reach a two-state deal in 2008.

In a radio address, the president said: "I am optimistic about the prospects."

But there are doubts Mr Bush can succeed where so many of his predecessors have failed.

There is also uncertainty around Israeli Prime Minister Ehud Olmert and Palestinian President Mahmoud Abbas' ability to close a deal, let alone implement one.

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