President Bush said the United States will press ahead with its role as a "catalyst" for Middle East peace despite obstacles to bringing the Israelis and Arabs to the negotiating table.

"I am not pessimistic," Bush said Thursday when reporters asked him to assess U.S. efforts in trying to arrange negotiations."I realize there are some strong, big obstacles, put it that way," the president said. "But I think everybody would agree that area of the world is long overdue for peace."

Secretary of State James Baker returned last Saturday from his third trip to the Middle East since the end of the gulf war, still unable to get the parties to agree to attend a proposed peace conference. There is disagreement about the format of the conference, including what role, if any, the United Nations would play. Also, there are questions about who would represent the Palestinians.

Bush said "there are no immediate plans" for Baker to make another trip to the Middle East "but that could change" on a short notice.

"I am determined that we are going to be the catalyst in that troubled corner of the world for peace," Bush said. "I think we're better positioned than we have been any time in the last years to be this catalyst for peace."

The president noted that the Arab-Israeli dispute has been going on "for many, many years . . . and you don't solve a problem of this complexity overnight." Bush said Baker had made "some progress and I wish I could share with you what it is. But when you're dealing in negotiations that are this sensitive, there are some things that are better kept on a quiet track and I'm just hopeful that we can build on the progress that's already been made."

During the last trip, Baker was able to obtain Soviet willingness to co-sponsor the conference and an agreement from Israel to accept such role.