President Barack Obama is beginning his latest bid to open a dialogue with the Muslim world by paying a call on Saudi King Abdullah, guardian of Islam's sacred sites in Mecca and Medina.

The monarch of Saudi Arabia plans to greet Obama at Riyadh's main airport with coffee and ceremony when he arrives Wednesday after an overnight flight from Washington.

Saudi Arabia is a stopover en route to Cairo, where Obama is to set deliver a speech that he's been promising since last year's election campaign — aiming to set a new tone in America's often-strained dealings with the world's 1.5 billion Muslims.

Many of those Muslims still smolder over Iraq, Guantanamo and unflinching U.S. support of Israel, but they are hoping the son of a Kenyan Muslim who lived part of his childhood in Indonesia, the world's most populous Muslim country, can help chart a new course.

"You know, there are misapprehensions about the West, on the part of the Muslim world," Obama said in a pretrip interview with the BBC. "And, obviously, there are some big misapprehensions about the Muslim world when it comes to those of us in the West."

Aides cautioned that Obama was not out to break new policy ground in his Cairo speech, which follows visits to Turkey and Iraq in April and a series of outreach efforts including a Persian New Year video and a student town hall in Istanbul. And they said the president is not expecting quick results, even though the speech will be distributed as widely as possible.

"We don't expect that everything will change after one speech," White House spokesman Robert Gibbs said Tuesday. "I think it will take a sustained effort and that's what the president is in for."

Officials said Obama also wouldn't flinch from difficult topics, whether it's the Iraq and Afghanistan conflicts, the goal of a Palestinian state or democracy and human rights. Obama has been criticized for setting the address in Egypt, where President Hosni Mubarak has jailed dissidents and clung to power for nearly three decades.

In Riyadh, the president was talking to Abdullah about a host of thorny problems, from Arab-Israeli peace efforts to Iran's nuclear program. The Saudis have voiced growing concern in private that an Iranian bomb could unleash a nuclear arms race in the region.

The surge in oil prices also was on the agenda. Crude topped $68 a barrel this week, sparking fears that a fresh jump in energy costs could snuff out early sparks of a recovery from a deep global slump.

Obama likely will be looking for help from Saudi Arabia on what to do with some 100 Yemeni detainees locked up in the Guantanamo Bay prison. Discussions over where to send the Yemeni detainees have complicated Obama's plan to close the prison. The U.S. has been hesitant to send them home because of Yemen's history of either releasing extremists or allowing them to escape from prison.

Instead, the Obama administration has been negotiating with Saudi Arabia and Yemen for months to send them to Saudi terrorist rehabilitation centers.

The president was to stay overnight at the king's horse farm in the desert outside Riyadh. Abdullah, who hosted then-President George W. Bush at the ranch in January of last year, keeps some 260 Arabian horses on its sprawling grounds in air-conditioned comfort.

In any effort to court Muslims, the Saudis will be key — not just for their oil wealth, but by virtue of the authority they wield at the center of Arab history and culture.

Obama's meeting with the 84-year-old Abdullah will be his second in three months. The two saw each other at the G-20 summit in London, a meeting both sides called friendly and productive. Perhaps a bit too friendly: Critics accused Obama of bowing to the Saudi monarch during a photo-op. The White House maintained he was merely bending to shake hands with a shorter man.

"This in many ways will be one of the pivotal relationships President Obama can develop," said Robin Wright, a scholar at the Woodrow Wilson Center. "Saudi Arabia is important not just in terms of the Gulf and oil prices. It sets the tenor. It's one of the most conservative regimes. It's also important because King Abdullah is, among the various royals, more open-minded than others. These are two men who might actually deal well with each other."