For Abbas, the U.N. bid is crucial if he wants to maintain his leadership and relevance, especially following the recent conflict between his Hamas rivals in Gaza and Israel. The conflict saw the Islamic militant group claim victory and raise its standing in the Arab world, while Abbas' Fatah movement was sidelined and marginalized.
The Palestinians chose the "International Day of Solidarity with the Palestinian People" for the vote. Before it takes place, there will be a morning of speeches by supporters focusing on the rights of the Palestinians. Abbas is scheduled to speak at that meeting, and again in the afternoon when he will present the case for Palestinian statehood in the General Assembly.
U.S. Secretary of State Hillary Clinton warned Wednesday that the U.N. vote will not fulfill the goal of independent Palestinian and Israeli states living side by side in peace, which the U.S. strongly supports because that requires direct negotiations.
"We need an environment conducive to that," she told reporters in Washington. "And we've urged both parties to refrain from actions that might in any way make a return to meaningful negotiations that focus on getting to a resolution more difficult."
The U.S. Congress has threatened financial sanctions if the Palestinians improve their status at the United Nations.
Ahead of the vote, Republican Sen. Orrin Hatch filed an amendment to a defense bill Wednesday that would eliminate funding for the United Nations if the General Assembly changes Palestine's status.
"Increasing the Palestinians' role in the United Nations is absolutely the wrong approach, especially in light of recent military developments in the Middle East," he said in a statement. "Israel is one of America's closest allies, and any movement to strengthen one of its fiercest enemies must not be tolerated."