WASHINGTON — President Bush, dispatching Vice President Cheney to the Middle East, said the goal is to get Israelis and Palestinian Arabs to hold firm to the promises they’ve made toward peace.

Mr. Bush said today in the Oval Office that Mr. Cheney would “reassure people that the United States is committed to a vision of peace in the Middle East.”

As Mr. Cheney tries to help hold together fragile negotiations between Israelis and Palestinian Arabs, Mr. Bush says he’s still optimistic that a peace deal can happen before he leaves office.

Mr. Cheney departs Sunday for a trip to Oman, Saudi Arabia, Israel, the West Bank, and Turkey. Oil is also on his agenda, as the White House — coping with high energy prices that have socked American consumers — continues to push for greater oil production in the Middle East.

The vice president’s visit comes on the heels of a brief troubleshooting mission to the Middle East by Secretary of State Rice. She was able to pressure the moderate Palestinian Arab leadership to resume peace talks with Israel, which broke off after a deadly Israeli military incursion into Gaza.

“I’m optimistic that we’ll be able to achieve a vision that shows a way forward, and I’m optimistic leaders will step forward and do the hard things necessary so people don’t have to live in deprivation and fear,” Mr. Bush said, addressing reporters after a meeting with Prime Minister Tusk of Poland.

In his final year in office, Mr. Bush has turned a Middle East peace deal into a signature foreign policy goal. But violence in the Gaza Strip and southern Israel has hampered the peace talks between Prime Minister Olmert and the president of the Palestinian Authority, Mahmoud Abbas. Mr. Cheney will meet with both men.

Palestinian Arabs have also condemned Israeli plans to build more housing in disputed east Jerusalem — an area the Palestinian Arabs hope to make the capital of a future independent state.

Mr. Bush made clear he expects Mr. Cheney to prod the leaders to stick to their obligations under the American-backed road map, which calls on the Palestinian Arabs to disarm militants and for Israel to halt settlement construction. “Those obligations are clear,” Mr. Bush said.

America blames recent violence on Hamas, which took over the Gaza Strip last July and is deemed by America to be a terrorist organization.

Without naming Hamas, Mr. Bush said: “There’s one force in the Middle East — and some suspect that they’re funded from outside governments and outside movements, all aiming to destabilize democracy, all aiming to prevent the vision where people can live side-by-side in peace, all wanting to destroy Israel.”

Mr. Bush said the key question is whether enough will exists to reject those extremist forces.

“Our mission is exactly along those lines, and I’m optimistic,” Mr. Bush said.

Today, Mr. Olmert instructed his army to halt airstrikes and raids into the Gaza Strip in response to a serious drop in rocket fire from the territory, allowing Egypt to proceed in its role as a mediator. Israeli defense officials and the Hamas rulers of Gaza said there was no formal truce in place.