RAMALLAH, West Bank - Palestinian President Mahmoud Abbas said today he will call a national referendum on accepting a Palestinian state alongside Israel if Hamas does not agree to the idea within 10 days.

Abbas' ultimatum to Hamas was a political gamble that could either help resolve the Palestinians' internal deadlock or lead them into a deeper crisis. Senior Hamas officials said they accepted the idea of a referendum.

Such a vote, which would ask Palestinians to give implicit recognition to Israel, could provide the hard-line group cover and allow it to moderate without losing face. Palestinian analysts believe such a proposal would pass.

Abbas' proposal came as Israeli Prime Minister Ehud Olmert returned from a trip to Washington, where he presented President Bush with a West Bank pullout plan. Olmert said if there is no breakthrough in long-stalled peace efforts in the coming months, Israel would withdraw from much of the West Bank, solidify its control of large settlement blocs and unilaterally draw its border with the Palestinians.

The Palestinians reject Olmert's unilateral plan, and Abbas' announcement today appeared part of a hurried effort to show the world there is a willing Palestinian partner for negotiations with Israel.

Abbas said that if 10 days of dialogue between Hamas and his Fatah movement did not lead to a joint political platform, he would call a referendum 40 days after that.

The referendum would ask Palestinians to either accept or reject a document that had been drafted earlier this month by senior Palestinian militants jailed in Israel. The five-page document calls for a Palestinian state in the West Bank, Gaza and east Jerusalem, the areas Israel captured in the 1967 Mideast War.

Hamas is pledged to Israel's destruction and has rejected international demands that it recognize the Jewish state or renounce violence. The group appeared to soften its position since taking power in March, but has refused to explicitly give up its demands for an Islamic state in all of historic Palestine, which includes Israel.

It was not clear whether Abbas had briefed Hamas before the announcement on the referendum. Some Hamas officials said they had been taken by surprise, but said they support the idea.

“Returning to the people is one of the most important principles in democracy,” said Parliament Speaker Abdel Aziz Duaik, of Hamas, who added that the prisoners' document was a good basis for dialogue.

The smaller Islamic Jihad group, which also rejects the existence of Israel, said it opposed the referendum proposal. Israeli officials declined to comment.

Abbas said a national consensus was needed urgently.

“The situation is getting more dangerous. The whole nation is in danger. We can't wait for the rest of our lives,” he said.

Yasser Abed Rabbo, a close adviser to Abbas, said Hamas and the other Palestinian groups had to make a choice, “either to accept the prisoners' document as it is or to go to a referendum.”

“Both solutions are satisfactory and can get us out of the impasse,” he said. “All that the international community needs is there in this document and we think that they will accept it.”

Palestinian pollster Nader Said of Bir Zeit University in Ramallah said he expected the referendum to pass because most Palestinians support a two-state solution.

“I think it has a very good chance to pass, I think it will get high support,” he said, estimating it could pass by as much as two-thirds.