"We should not continue in a vicious circle while life breaks down," Abbas said in a long-awaited speech Saturday. "We'll go back to the people and let the people decide."

Though Abbas was, in principle, invoking an executive privilege, Hamas accused him of seeking to topple its 9-month-old administration with the West's blessing.

"This is a real coup against the democratically elected government," said Mushir Masri, a lawmaker with the Islamic terrorist group. Hamas was elected last January and took office in March, prompting a cut-off of Western aid.

Abbas didn't set a date for new elections, and it's not clear how exactly the process would proceed, as P.A. law is vague on electoral procedures. Hamas claimed Abbas was free to resign as president, but had no authority to call new parliamentary elections.

Fighting quickly flared after Abbas' announcement. In the Gaza Strip, shots were fired at the convoys of the P.A. prime minister and foreign minister, both of them Hamas leaders, and gunmen killed an Abbas bodyguard in a separate incident. U.S.-trained security forces loyal to Abbas fanned out around government buildings.

In the streets of the West Bank, there were violent scuffles between Hamas loyalists and supporters of Abbas' Fatah faction.

In Jerusalem and Western capitals, the whirlwind developments drew mixed reactions.

While no one was upset to see Hamas under pressure, neither was the prospect of intra-Palestinian bloodshed welcomed. Even if new elections -- anticipated in mid-2007 -- are held peacefully, there is no guarantee that Hamas won't be re-elected. That surely would sound Fatah's death knell and confirm that the Palestinians are irrevocably taking a radical road.

The Israeli government, which long has called on Abbas to honor his international commitments by cracking down on Hamas and other Palestinian terrorist groups, fell silent Sunday. Political sources said Prime Minister Ehud Olmert had ordered his Cabinet colleagues to keep mum on the P.A. crisis.

That decision won rare praise from Ahmed Tibi, an Israeli Arab lawmaker and confidant of top Fatah officials. Any overt Israeli action to help Abbas "would only weaken Fatah," Tibi told Army Radio in an interview.

While he voiced worry at the violence in the West Bank and Gaza, Tibi predicted that Abbas would try to leverage the threat of new elections into talks that would prod Hamas toward compromise.

But Hamas has proven resilient, weathering a Western aid blockade on the Palestinian Authority and refusing to accommodate international demands that the Palestinian government recognize Israel's right to exist, renounce terrorism and honor past P.A. commitments.

The United States was less reticent than Israel about the Palestinian Authority crisis.

"While the elections are an internal matter, we hope this helps bring the violence to an end and the formation of a Palestinian Authority committed to 'the Quartet' principles," White House spokeswoman Jeanie Mamo said.

The "Quartet" is a diplomatic grouping made up of the United States, Russia, the European Union and the United Nations that's guiding the "road map" peace plan.

British Prime Minister Tony Blair, who was due to arrive later Sunday for a troubleshooting visit to Israel and the Palestinian Authority, spoke in Abbas' defense.

"This is the moment for the international community to come behind him, to help build his authority and his capability, to deliver improvements in the living standards of the Palestinian people, but also in the progress that we all want to see on resolving the Israel-Palestinian issue," Blair said.

"Hamas at the present time is not prepared to be constructive," he added. "I think he [Abbas] is serious about elections."