George Mitchell held separate talks Friday with Israeli and Palestinian leaders to try to find common ground.
However, the gaps remain so wide that the US has struggled to launch even indirect talks, in which Mitchell would shuttle between the two sides.
The Palestinians balk at engaging in so-called proximity talks unless Israel pledges not to start new construction for Jews in East Jerusalem, the Arab sector of the city the Palestinians want as a future capital.
Israeli Prime Minister Benjamin Netanyahu has rejected Washington's calls for a halt to new settlements in East Jerusalem and has seen tensions with Israel's most important ally rise dramatically on his watch.
Going into his meeting with Palestinian President Mahmoud Abbas on Friday evening, Mitchell said the US would not be deterred. “Comprehensive peace in the region will not be just a dream,” he said. “It must be and can be a reality. We want to make that reality happen, and soon, not in some vague and distant future time.”
Despite the challenges, the US would persevere “until we reach our common goal” of Israel and a Palestinian state living side by side in peace, he said.
Earlier, Netanyahu told Mitchell that Israel would be a constructive partner. “I look forward to working with the Obama administration to move peace forward,” Netanyahu said. “We are serious about it, we know you are serious about it and we hope the Palestinians respond.”
The prime minister's office said the meeting went well and Netanyahu and Mitchell would meet again on Sunday.
Netanyahu said in a televised interview Thursday that there would be no construction freeze in East Jerusalem, repeating a position that has brought him into conflict with Obama.
Israel annexed East Jerusalem in 1967, and the area is now home to around 180,000 Jews and 250,000 Palestinians. Israel sees the eastern sector of the city as part of its capital, while Palestinians want it for their own capital.
Nonetheless, Israeli government officials said Friday they were optimistic that indirect negotiations between the sides would be announced during Mitchell's visit, allowing Israelis and Palestinians to begin negotiating again for the first time since late 2008.
