Palestinian Authority President Mahmoud Abbas took Hamas leaders by surprise on Thursday by presenting an ultimatum to the struggling, newly-elected Palestinian government. Give up the struggle for "all of Palestine" within 10 days, or watch the Palestinian people vote in a referendum that could undermine Hamas's position on Israel.

Abbas urged Hamas leaders to sign an 18-point plan drafted last month by jailed militants from Fatah and Hamas -- many of whom are Palestinian freedom fighters -- which calls for a Palestinian state within the 1967 borders, meaning Hamas would be forced to relinquish its formal call to "liberate all of Palestine." "If you don't agree," said Abbas, "I will ask my people directly whether they accept or do not accept this plan."

Abbas clearly believes that popular support for Hamas has more to do with the party's promise to fight corruption than with its refusal to recognize Israel. His move seemed to wrong-foot Hamas leaders at a "national dialogue" among Palestinian groups in the West Bank and Gaza on Thursday. Prime Minister Ismail Haniyeh left the conference quickly without making a comment, but Hamas spokesman Ghazi Hamad said there was no need for a referendum and that Hamas would honor the results if it did come to a vote.

"We were elected on our platform but if people make another decision we will respect the decision of our people," he said. "… We aren't against political compromise."

Western governments have withheld hundreds of millions of dollars in aid  to the Palestinians ever since Hamas, considered a terrorist organization by Israel, the EU and the US, swept into power last January, because the group refuses to accept a Jewish state. Abbas was elected separately in 2005, and a struggle between his Fatah party and Hamas radicals  has deteriorated over the past two weeks into lethal shootouts and kidnappings. The "national dialogue" was called on Thursday to keep the conflict from sliding to civil war. "The homeland is in danger and we can't wait," said Abbas at the conference. "… As of tomorrow the countdown will begin. We must not resort to arms, because Palestinian blood is sacred."

The document  likely won't please Israeli leaders. It calls liberating Palestinian prisoners a "sacred national duty," encourages "resistance" within the West Bank and the Gaza Strip, and demands a capital in East Jerusalem. It doesn't even refer in so many words to Israel's right to exist, and since it falls short of accepting two further conditions for international aid -- renunciation of violence and ratification of past peace accords -- there was no guarantee that signatures by Hamas leaders on the document would end the boycott. But a referendum on the plan could give Hamas a way to back down from its anti-Israeli posture without losing face.

A referendum could also force Israel to the bargaining table. Israeli Prime Minister Ehud Olmert has vowed to set the country's final borders by finishing a controversial wall -- but a public show of support for a two-state solution by the Palestinian people could scuttle any unilateral move.

Israeli Foreign Ministry spokesman Mark Regev called the plan an "internal Palestinian matter" but said his government was following developments. Interior Minister Ronnie Bar-On said that as long as Hamas failed to accept the three international conditions, Abbas' gambit "is like playing checkers with himself."