George Mitchell, the Obama administration's special envoy for Middle East peace, plans to set a deadline for an Israel-Palestinian agreement, applying lessons learned from his successful mediation in a previous conflict.

Mitchell, delivering the keynote address Monday night to commemorate the 25th anniversary of the U.S. Institute of Peace, said that "no two conflicts are the same." But he noted that he had "established a deadline" that led to the Good Friday agreement of April 10, 199,8 that ended the bloody, decades-long conflict between Roman Catholics and Protestants in Northern Ireland.

Asked after the speech whether he intended to set a similar deadline for Israeli-Palestinian negotiations, Mitchell said that he would do so after indirect talks between the two sides progress to direct negotiations.

"We will [have a deadline] once we do" make that transition, he said. He did not say how much time he would give the parties to agree.

In his speech, Mitchell, who last week concluded two rounds of indirect talks in the Middle East, said he will move "as soon as possible" to direct negotiations.

In his public remarks, the former Senate majority leader acknowledged widespread skepticism both in the region and in Washington that he can broker a deal between the center-right government of Israel Prime Minister Benjamin Netanyahu and the Palestinian Authority of President Mahmoud Abbas.

So far, the skeptics would seem to have the better of the argument, with little discernable narrowing of the gaps between the two sides since Mitchell was first appointed to his role -- on the second day of President Obama's term.

But Mitchell said there had been significant progress since the Obama administration took office. He noted that the Netanyahu government has endorsed the concept of an independent Palestinian state and agreed to freeze new housing construction on the West Bank for 10 months. The Palestinians, the envoy said, are working to stop attacks on Israel and have made "substantial improvements in law and order and economic development" in the West Bank. The Arab League has also endorsed the indirect negotiations, known as "proximity talks," he added.

Mitchell said that the proximity talks "are serious and wide-ranging, with both sides trying to move forward under difficult circumstances." All sides, he said, "know more or less what a solution looks like." He repeated what, since the latter part of the George W. Bush administration, has become a mantra for framing the dispute: an end to the occupation that began in 1967, a "viable, contiguous, sovereign, and independent" Palestinian state and "secure, recognized and defensible borders" for Israel.

Mitchell omitted mention of the toughest issues impeding Israeli-Palestinian peace: the fate of Jerusalem and of Palestinian refugees. But he insisted that the situation "is not hopeless" and promised that he will "persevere" in his efforts to end the conflict.

"The tragedies of the past need not determine the opportunities of the future," he said. "There is no such thing as a conflict that can't be ended" if leaders demonstrate courage and political will.

The audience of several hundred at the Four Seasons Hotel responded to Mitchell's remarks with a standing ovation.