WASHINGTON — As Secretary of State Condoleezza Rice and Secretary of Defense Robert Gates head out Monday on a rare joint trip to the Middle East, it's not clear what they can accomplish.

Aides to Rice and Gates say the trip has three primary goals, each crucial: to persuade Iraq’s neighbors to do more to help stabilize the country, to counter Iran’s growing ambitions and to try to get real movement on peace between Israel and the Palestinians.

But America's credibility in the region has plummeted. The U.S. has failed to stabilize Iraq, destroy al Qaida, pacify Lebanon, isolate Syria or bolster moderate Palestinians. Instead, its policies have fueled Sunni Muslim extremism and emboldened Shiite Iran, which America's moderate Arab allies consider the two greatest threats to their rule.

So far, its support for Israel's ill-fated war in Lebanon and its efforts to undermine popular radical groups such as Hamas in the Gaza Strip and Hezbollah in Lebanon have borne little fruit. Along with its support for autocrats such as Egypt's Hosni Mubarak, such actions have undercut American claims that it's championing Muslim democracy.

Meanwhile, the clock is ticking on the Bush administration’s time in office. Leaders of friendly Arab states have lost confidence in President Bush’s ability to deliver on his promises and are wary of sticking their necks out too far to cooperate, according to diplomats and some U.S. officials.

“Our credibility is in tatters. They are not going to commit because they don’t trust us. That doesn’t mean they are not concerned about Iran. It just means they just don’t know what we are going to do,” said one senior State Department official, who spoke on condition of anonymity because he wasn't authorized to speak to reporters.

There are also signs of disarray within the administration.

On the eve of the trip, unnamed U.S. officials told The New York Times that Washington believes Saudi Arabia has been unhelpful in Iraq by not supporting Prime Minister Nouri al Maliki's government. The administration publicly disavowed the report, but said that Saudi Arabia could do more to help. The leaked complaint seems unlikely to make life easier for Rice and Gates when they arrive in Jeddah, Saudi Arabia, early in the trip.

The Bush administration also is divided over Iran, with Vice President Dick Cheney’s office pushing for an aggressive military response to Iran's reported aid and training for Shiite militias attacking U.S. troops in Iraq, senior officials said.

Gates and Rice will attend meetings together in Sharm al Sheikh, Egypt, and Saudi Arabia. Rice will then head for Israel and the Palestinian territories to meet with Israeli leaders and Mahmoud Abbas, the weakened Palestinian Authority president whose administration was run out of Gaza by the Islamist group Hamas. Gates is scheduled to visit other gulf states.

Senior Pentagon and State Department officials said the trip is intended to reassure Arab leaders that the U.S. will uphold its security commitments in the region, even as Congress debates pulling troops out of Iraq.

But Arab diplomats in Washington said their governments need more than reassurance. They said that while the U.S. has promised a more active role, they haven't seen a clear plan for Middle East peace or regional security.

Indeed, after Bush called two weeks ago for an international Middle East peace conference, some Arab leaders concluded that the speech lacked specific goals and simply repeated the broad hopes that he's articulated before — stability in the region and moderate, inclusive governments.

“There is no clarity,” one Arab diplomat said on condition of anonymity because he didn't want to disagree publicly with the administration. “The trip in and of itself is not important. What’s important is that the administration commit to dealing with the substantive issues.”

The gulf states want to know how a possible drawdown of troops in Iraq would affect their security and whether it would lead to fewer troops in other parts of the region.

More than what Rice and Gates say on the trip, “people are monitoring the debate in Washington. Everybody is watching that very closely and then will draw their own conclusions,” an Arab official in Washington said.

Sunni-led gulf states fear Iran, but aren't confident that the United States has a strategy for dealing with Tehran, the diplomats said. U.S. officials say they're in the early stages of building an alliance with the gulf states.

“Iraq may be an immediate destabilizing influence. But Iran is something we collectively need to deal with in the long term,” said Geoff Morrell, a Pentagon spokesman.

On the Israeli-Palestinian conflict, Saudi Arabia, Egypt and other U.S. allies in the region want the United States to reach out to Hamas, which now controls Gaza. But Rice has repeatedly ruled out dealing with the group, which is on the U.S. list of terrorist organizations.

"The strategy is based on the assumption that you could isolate, weaken ... Hamas," while strengthening Abbas and his Fatah faction, said Shibley Telhami, a Middle East expert at the University of Maryland. "It cannot succeed. ... Everybody agrees that you can't simply isolate Hamas."

Gates and Rice will encourage Arab leaders to attend the international meeting on Middle East peace that Bush called for in a July 16 speech. The gathering is tentatively scheduled to take place this fall.

Israel and the United States hope that officials from Saudi Arabia, other Persian Gulf states and Morocco — none of which recognizes Israel — will attend. But that appears far from assured.

Before the Iraq war, Washington had strong ties with the gulf states, especially Saudi Arabia. But the overthrow of Saddam Hussein’s Sunni-dominated government and the rise to power of Iraq’s majority Shiites shifted the balance in the region. With an unstable Iraq and their own Shiite minorities politically awakened, many governments feel U.S. actions have weakened their grip on power.

Some countries, such as Egypt, have maintained close ties with Washington, but Saudi Arabia and others have begun to distance themselves.

Rice and Gates have their work cut out for them. With 18 months left in office, it will be difficult to reshape the way the region sees the United States, said William Quandt, a professor of international relations at the University of Virginia, who as an aide to President Jimmy Carter helped craft the 1978 Camp David accords between Israel and Egypt.

“I don’t think they have a real strategy that has much chance of working,” Quandt said. Gates, who joined the administration in December, “may be able to calm things down a little. But that won’t change the course.”