WASHINGTON — President Bush’s top diplomatic and military managers have a tough assignment in the Middle East in the week ahead: convince skeptical Arab nations they have more to lose if Iraq fails than they stand to gain by waiting until America leaves or Mr. Bush’s term ends.

Secretary of State Rice and Defense Secretary Gates will visit Egypt and Saudi Arabia for a rare joint lobbying effort to prod Iraq’s mostly rich, Sunni-led Middle East neighbors to help stabilize the chaotic country and support its weak Shiite-headed government.

Mr. Gates and Ms. Rice also will do some handholding with Arab allies worried that America may leave a dangerous vacuum if it withdraws troops too quickly. The Cabinet secretaries also will try to solidify what the American government sees as a bulwark of generally moderate Arab states against an increasingly ambitious and unpredictable Iran.

Unity against Iran is not a hard sell. But Washington has had far less success in rallying Arab help for Iraq that goes much beyond words. Arab money and diplomatic support has lagged behind Europe’s, and some of Iraq’s neighbors quietly tolerate, or may secretly support, attacks inside Iraq. Some of the violence targets U.S. forces and some of it Shiite militias and neighborhoods.

“The United States wants to persuade all the countries in the region to be proactive in a helpful way,” said Samir Sumaida’ie, Iraq’s ambassador to Washington. “Waiting and watching is not a helpful posture.”

Other Arab diplomats, speaking on condition of anonymity, said waiting and watching is exactly what they plan to do, at least as long as the killing does not spread beyond Iraq’s borders and the U.S. is trying to stand in the sectarian breach.

“There is the general sense that no one wants to get aboard a sinking ship,” said one diplomat, who like others requested anonymity to describe sensitive discussions within his government and with American officials.

Arab states with restive Sunni populations see little advantage in giving overt support to a government in Baghdad seen as hostile to Sunnis, even though Arab leaders fear a wave of unrest or civil war if Iraq collapses, diplomats said. That fear may be Mr. Bush’s strongest card, but he has declining leverage as his term winds down. He leaves office in January 2009.

Envoys from eight Persian Gulf and other Middle East nations will hear from Ms. Rice and Mr. Gates at a regional meeting tomorrow. It is to take place at the same Egyptian resort that hosted a major international conference on securing Iraq nearly three months ago. Little has happened since, despite specific pledges of help and the formation of committees meant to help Iraq solve some of its toughest problems. The committees have yet to meet, although there are plans to do so shortly.