RAMALLAH, West Bank – Formal Palestinian approval of indirect talks with Israel cleared the way Saturday for President Obama’s first sustained on-the-ground attempt to bring peace to the Middle East.

Former Maine Sen. George Mitchell, the White House envoy to the Mideast, will try in four months of shuttle diplomacy to rebuild trust between Israeli and Palestinian leaders and narrow some of their vast differences, in hopes of nudging them toward direct negotations.

However, expectations are low and obstacles seem insurmountable. The Israelis and Palestinians remain far apart on what a Palestinian state should look like. Talks are being overshadowed by Israel’s refusal to halt settlement construction on war-won land, and the rule of the Islamic militant Hamas in the Gaza Strip, one of the territories that would one day be part of a Palestinian state.

The indirect format also looks like a big step backward, following 16 years of direct, if intermittent, negotiations, including frequent meetings just two years ago between Palestinian President Mahmoud Abbas and Israeli Prime Minister Benjamin Netanyahu’s predecessor.

Abbas has said he will not hold direct talks until Israel stops all settlement construction in the West Bank and east Jerusalem, the sector of the city Palestinians claim as a future capital. Israel has agreed to a temporary slowdown in the West Bank, but not in east Jerusalem.

The indirect talks were devised as a compromise, but the arrangement was thrown into doubt in March when Israel announced new plans to build 1,600 homes for Jews in east Jerusalem. The decision, which came just as Vice President Joe Biden arrived in Israel for a visit, drew sharp criticism from the United States and led to the worst spat between the allies in years.

The settlement announcement also enraged the Palestinians, prompting them to back out of negotiations just as talks were to start. Since then, the United States has worked to coax the Palestinians back to the table.

On Saturday, leaders of the Palestine Liberation Organization and Abbas’ Fatah movement voted to give indirect talks a try. The decision had been widely expected because Abbas, with backing from the Arab League, has already said he wants to pursue the opportunity.

Yasser Abed Rabbo, the PLO secretary general, said the Palestinians received assurances from the Americans concerning “settlement activities and the necessity to halt them.” He said the Obama administration also promised to be tough in the event of “any provocations,” presumably new settlement plans, and guaranteed that all so-called core issues would be on the table.

Palestinian negotiator Saeb Erekat said the talks would focus on the borders of a Palestinian state and security arrangements. The Palestinians want the West Bank, Gaza and east Jerusalem for their state, but have said they are willing to make some minor land exchanges to enable Israel to annex some West Bank settlements.