|Mitchell, far right, is stepping down as peace talks between Israel and the Palestinians are at a standstill [AFP]
George Mitchell, the Obama administration's special Middle East peace envoy, has resigned after more than two years of trying to press Israel and the Palestinians into negotiations, US officials said.
The White House announced on Friday that the former senator and broker of the Northern Ireland peace deal had stepped down for personal reasons.
"[Mitchell's] work has brought peace and increasing prosperity to millions of people around the world and made our own country stronger and more secure"
US secretary of state
Accepting Mitchell's resignation, Barack Obama, the US president, said in a statement that the veteran mediator "has contributed immeasurably to the goal of two states living side by side in peace and security".
"As a nation, we remain committed to peace in the Middle East and to building on George's hard work and progress toward achieving this goal," he said.
David Hale, the deputy Middle East envoy, has been asked to serve as the acting envoy by Hillary Clinton, the US secretary of state.
"I have every confidence in David's ability to continue to make progress in this important effort," Obama said.
Al Jazeera's Patty Culhane, reporting from Washington, said Mitchell's resignation could be "a sign or symbol that the Obama administration is going to refocus its efforts on the Israeli-Palestinian process".
"Mitchell did make a push for peace, but weeks later it fizzled because of Israel's refusal to stop the settlement building. Since then it really has dropped out of the headlines in the US," she said.
Mitchell, 77, had spent much of the last two years shuttling between the Israelis and Palestinians in a bid to restart long-stalled peace talks.
Direct peace talks resumed briefly last year but broke down over Israeli settlement construction on occupied land.
Faced with deadlock, the US in December scrapped efforts to relaunch direct peace talks and Mitchell
has not visited the region since then.
In recent months, his activity had slowed markedly as the two sides drifted farther apart.
"From the Senate to Northern Ireland to the State Department, his work has brought peace and increasing prosperity to millions of people around the world and made our own country stronger and more secure," Clinton said in a statement on Friday.
Obama has recently made changes to his Middle East policy team and named Daniel Shapiro, a senior adviser who has helped shape the response to the Middle East upheaval, as his nominee to be the new US ambassador to Israel.
"We've been hearing from the White House that president Obama is going to give a big speech where he'll place a new focus on the Middle East peace process," said Culhane.