Palestinian president Mahmud Abbas was to meet Arab diplomats in New York Tuesday ahead of a fresh bid at the United Nations to create a new "political reality," his spokesman said.
"This visit is going to be a very important one, a crossroads," Nabil Abu Rudeina told Voice of Palestine radio.
"Settlements must stop. Israel must be forced to accept international legitimacy and law," he said.
"If it does not, there will be another political reality to deal with. The next few weeks will see developments that will affect the peace process in the future."
Since the collapse of US-led peace talks with Israel in April, the Palestinians have been pursuing a new diplomatic path to independence via the United Nations and through joining international organisations.
During the UN General Assembly, which opens Wednesday, Abbas plans to propose a three-year deadline for ending the Israeli occupation and establishing a Palestinian state within the 1967 lines.
He will meet the Arab group "to devise a unified position for making the next move towards establishing a state," Abu Rudeina said.
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"Things are critical right now, but the Palestinians and Arabs are determined to go to the (UN) Security Council and demand international protection," he told the radio.
Speaking to students in New York Monday, Abbas confirmed he would lay out "a new timetable for peace talks."
Abbas will meet US Secretary of State John Kerry Wednesday to lay out details of his initiative.
"If he rejects it, the leadership has other options. We will go to international agencies and the Security Council," Abu Rudeina warned.
But if Abbas's proposal were put to the Security Council, it would likely be vetoed out of hand by the United States as a "unilateral move."
Last week, Abbas held talks with French President Francois Hollande, who confirmed that a "solution to the conflict" would be put to the Security Council because years of stop-start negotiations had gone on "too long."
"We will have a resolution, to be presented to the Security Council, that will say very clearly what we expect from the (peace) process and what the solution to the conflict must be," Hollande told reporters, without elaborating.
In 2012, the Palestinians won the status of UN observer state. That gives them the ability to become a party to the International Criminal Court, where they could sue Israeli officials over allegations of war crimes.