The United States is urging Israeli-Palestinian security cooperation in the run-up to Sunday's Palestinian presidential election. The State Department said Friday it hopes for a free and fair vote that yields a "credible result."

The final phase of the campaign has been marred by disputes over Israeli restrictions on the Palestinian candidates' access to East Jerusalem.

But Israel has taken down some West Bank checkpoints and been working with Palestinian security services to facilitate the campaign and balloting, and U.S. officials are hoping the cooperation continues through, and beyond, Sunday's voting.

At a news briefing, State Department Deputy Spokesman Adam Ereli said the extent and productiveness of the cooperation between the sides in the run-up to the election is worthy of praise, and a hopeful sign about their future relations under a newly-elected Palestinian leadership. "We certainly would hope that what we've seen in this instance will lead to further steps towards cooperation and engagement. So in short, they've been working well together so far. It's important that they continue to work well together to have a successful election. And for our part, we'll judge that election by whether, and to what degree, it produces a free, fair and credible result," he said.

The United States is joining countries around the world and international organizations in sending observers to monitor Sunday's vote.

The official U.S. observer team is headed by Republican Senator John Sununu and his Democratic colleague Joseph Biden, the ranking Democrat on the Senate Foreign Relations Committee.

The delegation also includes several Congressional staff members and prominent Palestinian-Americans George Salem, Chairman of the Arab-American Institute, and Ziad Asali, President of the Arab-American Anti-Discrimination Committee.

The U.S. delegation, being joined in the region by U.S. Consul-General in Jerusalem David Pearce, will visit polling sites, meet with senior Palestinian and Israeli officials, and before departing make an assessment of the election process.

Private Americans are also among the observers, including former President Jimmy Carter.

Wednesday, the State Department issued an updated travel warning for Israel, the West Bank and Gaza on security issues related to the Palestinian elections.

It said U.S. officials are "particularly concerned" that Palestinian extremists, especially in Gaza, may attempt acts of violence against international election observers in an effort to undermine the Palestinian Authority's ability to conduct a free and fair vote.

The State Department has for many months advised U.S. citizens to avoid Gaza and to defer travel to Israel and the West Bank.