WASHINGTON — President Bush, capping an intense flurry of diplomacy, said today the agreement by Israeli and Palestinian Arab leaders to resume long-stalled peace talks was “a hopeful beginning.”

Mr. Bush was joined in the White House Rose Garden by the Palestinian Authority president, Mahmoud Abbas, and Prime Minister Olmert in a brief ceremony a day after they agreed in Annapolis, Md., to try to reach a Middle East peace settlement by the end of 2008.

“One thing I have assured both gentlemen is that the United States will be actively engaged in the process,” Mr. Bush said. “We will use our power to help you as you come up with the necessary decisions to lay out a Palestinian state that will live side-by-side in peace with Israel.”

“Yesterday was an important day, and it was a hopeful beginning,” Mr. Bush said with the leaders at his side. “No matter how important yesterday was, it’s not nearly as important as tomorrow and the days beyond. I appreciate the commitment of these leaders, working hard to achieve peace. I wouldn’t be standing here if I didn’t believe that peace was possible, and they wouldn’t be here either if they didn’t think peace was possible.”

Unlike their three-way handshake yesterday, the leaders did not shake hands in the Rose Garden.

“I appreciate your courage and leadership,” Mr. Bush said. “It’s an honor to call you friends. And it’s an honor to have watched you yesterday as you laid out your respective visions for something we all want, which is peace in the holy land.”

After meeting their own low expectations for the Annapolis conference amid intense skepticism, Bush administration officials crowed with delight.

“What has been remarkable about this process is that they are now ready to go,” Secretary of State Rice told ABC during a round of TV interviews this morning in which she praised unprecedented support for the peace process from Arab states.

“It’s going to be hard, but you had support in that room that you had not had from Arab states in the past,” Ms. Rice said on NBC.

After inaugurating the negotiations at the White House, the two sides have agreed to continue with a meeting in the region on December 12, Ms. Rice said yesterday.

Mr. Bush, along with Ms. Rice, had earlier salvaged a “joint understanding” between the Israelis and Palestinian Arabs, who had remained far apart on the details of the statement until the last minute.

But with prodding from the American side, Messrs. Olmert and Abbas — troubled leaders with fragile mandates for peace — told international backers and skeptical Arab neighbors they are ready for hard bargaining toward an independent Palestinian Arab state in the 14 months Mr. Bush has left in office.

“This is the beginning of the process, not the end of it,” Mr. Bush said yesterday after reading from the just-completed text the statement that took weeks to negotiate and yet sets only the vaguest terms for the talks to come.

“I pledge to devote my effort during my time as president to do all I can to help you achieve this ambitious goal,” Mr. Bush told Messrs. Abbas and Olmert as the three stood together in the U.S. Naval Academy’s majestic Memorial Hall in historic Annapolis, Md.

“I give you my personal commitment to support your work with the resources and resolve of the American government.”

The two Middle East leaders were circumspect but optimistic.

“I had many good reasons not to come here,” Mr. Olmert told diplomats, including those from Arab states that do not recognize Israel like Saudi Arabia and Syria. “Memory of failures in the near and distant past weighs heavy upon us.”

Mr. Abbas, meanwhile, recited a familiar list of Palestinian Arab demands, including calls for Israel to end the expansion of Jewish settlements on land that could be part of an eventual state called Palestine and to release some of the thousands of Palestinian Arab prisoners in Israeli jails.

“Neither we nor you must beg for peace from the other,” Mr. Abbas said. “It is a joint interest for us and you. Peace and freedom is a right for us, just as peace and security is a right for you and us.”

In another development, a former NATO commander is expected to accept a role as adviser to Ms. Rice on security issues related to the negotiations between Israel and the Palestinian Arabs, officials close to the discussions said today. Ms. Rice was expected to announce later in the day that the advisory post would be taken by a retired Marine Corps general, James Jones, who was the alliance’s top commander in Europe. The officials spoke on condition of anonymity because there has been no official announcement.

A State Department spokesman, Sean McCormack, said the administration would announce a new position that involves monitoring the development of Palestinian Arab security services. One focus would be how those forces interact with neighboring security services, including Israeli authorities. Mr. McCormack did not say who would fill the position.

America has pledged not only to be actively involved in the peacemaking process, but to also hold both sides to account if they do not carry out obligations.