WASHINGTON AND LONDON — During a grinding 18-month stretch in the 1990s, U.S. envoy George J. Mitchell crossed the Atlantic more than 100 times in a dogged search for peace between Northern Ireland's Protestants and Catholics.
Even though he is a Catholic, Mitchell convinced Protestant Unionists of his evenhandedness, eventually reaching the Good Friday agreement in 1998 to help settle the 800-year dispute.
"He's got this incredible patience to sit there until the deal is done," said Ross K. Baker, a political scientist and former congressional aide. Mitchell, he said, "deserves the iron trousers award."
President Obama hopes the former Senate majority leader, now his new Middle East peace envoy, is prepared to sit awhile longer in an effort to settle the conflict between Israelis and Arabs. At 75, Mitchell is widely considered up to the challenge.
"He understood the wheeling and dealing on the floor of the Senate, and he understood the one lesson that to get people to support something, everybody had to get something out of it," said Reg Empey, a Unionist who was involved in the Northern Ireland negotiations and is now a minister in the Belfast government.
Since leaving the Senate in 1995, Mitchell has taken on one seemingly intractable problem after another.
He led an inquiry on steroids use in baseball, mediated a corporate civil war as chairman of Walt Disney Co., investigated allegations of corruption at the Olympics, and twice has tried to settle the Middle East conflict.
The latest job "seems impossible to everybody else," said a former Democratic Senate staffer who worked with him. "To him, it's another assignment."
Obama and Secretary of State Hillary Rodham Clinton chose Mitchell to convey the administration's determination about Middle East peacemaking. In his new role, Mitchell will once again be working on a problem with Tony Blair, who was British prime minister at the time of the Good Friday agreement.
Blair now serves as Middle East envoy for the so-called quartet seeking peace in the region: the United States, the European Union, the United Nations and Russia.
Mitchell won a reputation for evenhandedness in his first foray into Middle East peacemaking, in 2000 and 2001, when he led a six-month fact-finding mission on the reasons behind a convulsion of Palestinian violence.
The Mitchell commission report gave each side something to like and dislike. It urged Israelis to halt all settlement activity and to stop shooting at unarmed demonstrators, and it called on Palestinian authorities to stop violence and punish those who commit it.
"Neither side was entirely happy, and that was a good thing," said Ghaith al Omari, who was then a Palestinian negotiator and is now with the American Task Force on Palestine, a Washington group favoring Palestinian statehood.
Mitchell's neutral approach may encounter more skepticism since the recent breakdown of a cease-fire between Hamas fighters in the Gaza Strip and Israel's ensuing three-week offensive.
A number of a pro-Israel and pro-Palestinian groups, as well as the Israeli government, have praised the selection of Mitchell. But some on the pro-Israel side have also expressed misgivings. They fear that the Obama administration could increase pressure on Israel to make concessions.
Although his mother was Lebanese, Mitchell has not been active in advocacy groups espousing Arab causes. His Senate voting record is considered solidly pro-Israel. He supported foreign aid packages for the Jewish state and regularly voted against sales of U.S. weaponry to Arab countries.
Morris Amitay, a former head of the American Israel Public Affairs Committee, praised Mitchell's Senate record and his public statements. But he said he was concerned by Mitchell's comments about the need to pressure both sides to move toward peace.
"It bothers me a bit," he said. "The Israelis have shown that they're the good guys. And the people they're being asked to make peace with are usually the bad guys, with a couple of exceptions."
The Mitchell commission report, which was ordered up by the Clinton administration in October 2000, was delivered in 2001 to the new Bush administration.
Both the United States and Israel endorsed it. But because violence was continuing, Al Omari said, it was "close to stillborn."
Nevertheless, some of its key ideas, such as its plans for step-by-step, reciprocal moves, were incorporated into later U.S. plans for peace.
Al Omari said Mitchell's approach was to consult widely, to convince participants of his sympathy to their goals, but also not to yield to pressure once he had reached conclusions.