Leading article: President Obama's ambitious realism

It is easy to list the potential pitfalls that might lie in wait for Barack Obama's Middle East strategy. The US President arrives in Saudi Arabia today for the first leg of his tour with the problems of the region looking as intractable as ever.

A right-wing government in Israel is thumbing its nose at the White House over the expansion of settlements. Voters in Lebanon on Sunday could deliver power to Hizbollah, whose militia fought a war with Israel only three years ago. And later this month elections in Iran could return the hardline president, Mahmoud Ahmadinejad, for another term. These look like unpromising conditions for a lasting settlement.

Yet there is a case for optimism. And that lies primarily in the fact that the US President is approaching these overlapping challenges in an eminently sensible manner. First, he is setting a conciliatory tone. He has stressed that he will not make the mistake of his predecessor in seeming to want to impose America's will on the Islamic world regardless of its own wishes.

Second, he is acting in a practical manner, refusing to hint at US support for any particular faction in the forthcoming Lebanese and Iranian elections. He knows that to do so would limit his room for manoeuvre down the line.

Finally, he is emphasising the need for patience. He knows any progress towards his objective of an all-encompassing regional deal on a two-state solution for Israelis and Palestinians will take time. It makes no sense to raise the alarm over every early setback. The US President has been criticised by left-wingers in his own country for failing to make a sufficiently clear break with the Bush administration on issues such as torture. But these domestic critics fail to give Mr Obama credit for what his foreign diplomacy has already achieved. As King Abdullah of Jordan remarked last month, President Obama enjoys rare credibility at the moment in the Middle East.

The conditions for progress in the region are better than they might at first appear. And the President's approach contains the right mix of ambition and realism. What he needs to signal this week is his determination to stick to the long and inevitably painful course ahead.