WASHINGTON — President Bush intends to reaffirm his commitment to Middle East peace and outline how America can help the Palestinian Arab leadership make the transition to a viable state that can exist with Israel, a White House aide said yesterday. In remarks planned for today, Mr. Bush is seeking to bolster the embattled Palestinian Arab president, Mahmoud Abbas. His Fatah Party now controls only the West Bank since the Islamic militant group Hamas wrested power in Gaza earlier this year.

National security adviser Stephen Hadley said Mr. Bush would discuss American financial and diplomatic support for Mr. Abbas’s Palestinian Authority.

“The president sees there is an opportunity there now to show the Palestinian people a choice between the kind of violence and chaos under Hamas in Gaza and the prospect, under President Abbas and Prime Minister Salem Fayyad for an effective democratic Palestinian state that can be on the way toward what we all want, which is a two-state solution, a Palestinian homeland for the Palestinian people,” Mr. Hadley said. Mr. Abbas, who is backed by Israel, consolidated his control of the West Bank on Saturday, installing an interim government of moderates.

While America, Israel, and other nations behind Mr. Abbas consider ways to support the West Bank leadership, Hamas called a special session of the Palestinian Parliament for yesterday to challenge the new government.

International negotiators trying to bring peace to the Middle East plan to meet Thursday in Portugal. The group, expected to include Secretary of State Rice, will confer with former British prime minister, Tony Blair, for the first time in his new role promoting peace between Israel and the Palestinian Arabs.

Top officials from America, the United Nations, the European Union, and Russia appointed Mr. Blair to the job after he stepped down as prime minister June 27. His task is to focus on mobilizing international support and assistance for the Palestinian Arabs.