By Sue Pleming

WASHINGTON, July 18 (Reuters) - The quartet of Middle East mediators is expected to back U.S. plans to revive Israeli-Palestinian peace moves and hear from new special envoy Tony Blair when it meets in Portugal on Thursday.

It will be the first session bringing together top diplomats from the United States, Russia, the European Union and the United Nations since Islamist Hamas took over Gaza last month and U.S.-supported Palestinian President Mahmoud Abbas formed a caretaker government in the West Bank.

"It's a good opportunity for them to get together, take stock of what has happened over the past couple weeks, as well as to look ahead and chart a course out for the next several months," State Department spokesman Sean McCormack said.

The meeting will mark Blair's first appearance as quartet special envoy.

The former British prime minister's mandate is to help build up Palestinian institutions and encourage economic development but some diplomats want him involved in peacemaking, a role dominated by U.S. Secretary of State Condoleezza Rice and one that Washington wants her to keep.

"There are mixed feelings in the Bush administration about how much rope Tony Blair should get," said Bruce Riedel, a former CIA analyst now at the Brookings Institution.

The quartet has thrown its weight behind Abbas, and is looking for more public expressions of support for the moderate Palestinian leader and greater isolation of Hamas.

The United States, the European Union and Israel consider Hamas a terrorist organization but Russia has been more open to dealing with the group.

"The issue of Hamas is front and center of all of this. I don't sense there is any unanimity on this issue," said Jon Alterman, a Middle East expert from the Center for Strategic and International Studies, a Washington think tank.

U.S. President George W. Bush this week announced plans for a Middle East peace conference in the autumn, probably in the United States, to bring together Israel, moderate Palestinian leaders and their Arab neighbors.

ENDORSEMENT

The quartet meeting in Lisbon is likely to endorse the conference, whose composition and goals are unclear.

"We want the international meeting to be an important step ... We said many times this has been a long overdue step," said the EU's foreign policy chief Javier Solana, speaking in Ramallah after meeting Abbas.

"I think the possibilities now of moving together (Israel and the Palestinians) are becoming better. I think a new momentum may be created," he said.

Egypt's Foreign Minister Ahmed Aboul Gheit said he hoped the quartet would lend authority to Abbas.

"We are also hopeful that the meeting tomorrow will help the launching of negotiation between Israelis and Palestinians, that would aim at realizing a final settlement and discussions on the end game," Gheit told reporters in Portugal, which holds the rotating EU presidency.

The Palestinians and the Israelis have not tackled any of the so-called "final status" issues -- the return of refugees, the status of Jerusalem, and the future outlines of a Palestinian state for years.

EU diplomats said the quartet had dropped for the moment the idea of holding a joint meeting with the Arab League's quartet -- Egypt, Jordan, Saudi Arabia and the United Arab Emirates -- and Israeli and Palestinian representatives, partly because Israel was not keen and preferred to pursue its bilateral track with Abbas. (Additional reporting by Paul Taylor in Brussels, Wafa Amr in Ramallah and Henrique Almeida in Lisbon)

AlertNet news is provided by