Updated 12:28 p.m. ET
JERUSALEM Israeli and Palestinian teams headed to Washington Monday for preliminary talks on resuming formal negotiations after five years of stalemate.
Both sides emphasized that many obstacles stand between them and a final deal on setting up a Palestinian state alongside Israel.
Talks will be complex, said Israel's chief negotiator, Tzipi Livni. She said she was heading to the Washington meetings, which were to begin later Monday, "cautiously, but also with hope."
Hanan Ashrawi, a Palestinian spokeswoman, said the upcoming talks are being held under more difficult conditions than previous negotiations. She cited the Palestinian political split, with Western-backed moderates and Islamic militants running rival governments, and the more hawkish positions of Israel's prime minister, Benjamin Netanyahu, compared to his predecessor.
"But I think there is a recognition of the urgency," she said. "If we don't move fast and decisively, things could fall apart."
The preliminary talks in Washington were made possible after Israel's Cabinet on Sunday agreed in principle to, convicted of offenses including the killing or wounding of Israelis and the killing of suspected Palestinian collaborators.
The prisoners are to be released in four stages, with each release linked to progress in negotiations.
The resumption of direct Israeli-Palestinian contacts was a result of six months of shuttle diplomacy by U.S. Secretary of State John Kerry.
Neither side appeared upbeat, despite the possibility of renewed talks. Each has blamed the other for the lack of success in 20 years of negotiations, and Kerry's only success so far has been to get the parties back to the table.
In a statement, President Obama called the moves so far "a promising step forward, though hard work and hard choices remain ahead."
The prisoner release, approved 13-7 with two abstentions, is a key part of the Kerry-brokered deal.
The Monday meeting in Washington, the State Department said, is designed to prepare for six to nine months of negotiations on setting up a Palestinian state alongside Israel.
The department said Kerry called Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas and invited them to send teams to Washington.
Kerry is expected to announce his appointment of Martin Indyk as the United State's new Middle East envoy, CBS News confirmed. Indyk, a former U.S ambassador to Israel, heads foreign policy studies at the Brookings Institution think tank.
Netanyahu, seeking to overcome stiff opposition from ultra-nationalists, told his Cabinet that "resuming the political process at this time is important for Israel," noting that any deal would be submitted to a national referendum.
The chief Palestinian negotiator, Saeb Erekat, welcomed the vote on the prisoners as a "step toward peace," one he said is long overdue.
Negotiators made progress in previous rounds, and the outlines of a deal have emerged -- a Palestinian state in most of the West Bank, Gaza and east Jerusalem, lands captured by Israel in 1967, with border adjustments to enable Israel to annex land with a majority of nearly 600,000 settlers.
Those negotiations broke down before the sides could tackle the most explosive issues -- a partition of Jerusalem and the fate of Palestinian refugees and their descendants, now several million people.
Aaron David Miller, a former senior U.S. advisor on Arab-Israeli security, told CBS New correspondent Margaret Brennan the gap between the sides on the border and security issues is not that large. However, when it comes to the issues of Jerusalem and refugees, "think Grand Canyon."
Abbas remains leery of negotiating with Netanyahu, fearing any offer made by the hard-liner would fall far short of Palestinian demands, so he has insisted on a clear framework for negotiations.
Abbas said over the weekend that Kerry assured him the invitation to the negotiators will say border talks are based on the 1967 line, though Netanyahu has not said whether he has dropped his long-standing opposition to that demand.
In Washington, the Israeli and Palestinian teams are supposed to close the remaining gaps on the framework for talks, and they could well falter at that early point.
Israel's release of veteran prisoners could help Abbas persuade a skeptical Palestinian public that it's worthwhile returning to negotiations.
Netanyahu has repeatedly called for a resumption of negotiations that broke down in 2008, but he has not sketched the outlines of a deal he would be willing to strike, except to say he opposes a partition of Jerusalem.
In Sunday's Cabinet meeting, he pushed through the prisoner release despite opposition by two ministers in his Likud Party and by those from a main coalition partner, the pro-settler Jewish Home Party.
Outside the government complex, hundreds protested against a release. Among them were families of Israelis killed in attacks by Palestinian militants. Some held up pictures of their loved ones.
Naftali Bennett, the head of Jewish Home, briefly joined the protesters before attending the Cabinet meeting. "It's a hard day, the decision was made and I hope we won't pay a horrible price for this in the future," he said after the vote.
In the West Bank and Gaza, some relatives of prisoners anxiously awaited word. "Now there is a big relief," said Walid Abu Muhsen, 45, whose brother Jamal has been in prison for the past 22 years for killing an Israeli farmer.
The first disagreements emerged just hours after the Cabinet vote, reflecting the hostility and deep mistrust between the two sides.
Under the deal brokered by Kerry, Israel is supposed to free 104 prisoners who carried out attacks before the first interim peace agreements of the early 1990s.
Palestinian negotiators handed Kerry a list of 104 prisoners, arrested between 1983 and 1994. They said Kerry assured them Israel would release the prisoners in four stages over several months, with each release linked to progress in negotiations.
Among the 104 prisoners on the Palestinian list are two dozen who either have Israeli citizenship or come from Israeli-annexed east Jerusalem. In the past, Israeli media have said Israel would not free them.
On Sunday evening, an official in Netanyahu's office said that no Israeli Arabs are among the 104 whose release was authorized by the Cabinet. Asked to explain the discrepancy, he said Israel holds more than 104 "pre-Oslo" prisoners, suggesting the two sides apply different definitions.
Issa Qarakeh, the Palestinian minister of prisoner affairs, responded angrily.
"The agreement with Kerry was that all the pre-Oslo prisoners, including Israeli Arabs and east Jerusalem residents, will be released," he said. "If they (Israelis) exclude any of them, there will be a problem that might hinder the talks."
Israeli analyst Yossi Alpher said that a prisoner release in stages gives Netanyahu additional leverage during negotiations.
"Netanyahu has given himself a carrot that he can hold out to the Palestinians," he said. "Netanyahu can refuse to release the later batches if there's no progress."