Threats could come from a new wave of Palestinian attacks, from Israel's government and the powerful pro-Israel lobby in the United States.

The endorsement of new Palestinian Prime Minister Mahmud Abbas this week has acheived one aim of the Bush administration in sidelining President Yasser Arafat.

The question is now whether Bush will insist that Israeli Prime Minister Ariel Sharon adopt a more moderate tone.

"Sharon will not show willing, but if Bush is really determined, he'll move," a Washington-based European diplomat said.

The roadmap, drawn up by the United States, the European Union, Russia and the United Nations, calls for a Palestinian state to be established by 2005.

Steve Riskin of the United States Institute of Peace (USIP) highlighted the political and logistical complexities of the roadmap, and the domestic opposition Bush would face in striving for its full implementation.

"Bush . . . says he is committed to this (roadmap), but when you scratch the surface of the document, look at the political line-up and look at what needs to be done . . . you quickly run up against very difficult obstacles," he said.

These obstacles include Jewish settlements in Palestinian territories, and whether moves by both sides should be simultaneous or dependent on progress by the other side, Riskin said.

Bush has said the United States will do everything possible to implement the roadmap, in concert with the other members of diplomatic 'Quartet' that drew up the blueprint, and stressed his willingness to work with Abbas.

While this is a significant shift from the ostracism shown towards Arafat, there is still a wide disparity between Bush's treatment of the Palestinian leadership and Sharon.

The hardline Israeli premier has visited Washington seven times over the past two and a half years, and an eighth official visit is mooted for the middle of May.

According to Riskin, this highlights splits in the administration whether the US should follow its traditional 'honest broker' role or adopt a more partisan pro-Israel stance. The debate is likely to become fiercer ahead of US presidential elections next year.

"There are a number of people in the administration who do not subscribe to the notion that one needs to pressure the Israeli government, and maybe some don't even buy the land-for-peace formula at all, and these are people that are rather senior," he said.

Any confrontation by Bush with this camp is likely to have domestic ramifications in an election year, Riskin noted.

"If he is committed to seeing this (roadmap) through, he is going to have to make some very difficult political decisions in the face of opposition from his key constituencies, including the Christian Right and significant parts of the Jewish community," Riskin observed.

However, other pundits say that if Bush maintains his resolve in tackling extremists on both sides, his international and domestic standing would be boosted.

Washington Post editorialist David Ignatius said: "If Bush can show that he is serious about the roadmap - and that he will not tolerate obstruction -- a sceptical world will applaud his leadership."

SPACE.WIRE