With Palestinians fighting one another and control of Gaza and the West Bank divided, former British Prime Minister Tony Blair has a daunting task ahead of him as he takes up his new job as envoy to the Middle East.

Even Blair’s political opponents concede that his tenacity and skill over an exhausting decade of two-steps-forward, one-step-back negotiations in Northern Ireland were key to the settlement that brought Catholics and Protestants back into joint government this spring.

He’s long argued that peace in the province once blighted by bombs and guns offered a hopeful example for Israelis and Palestinians, proving that it is possible to move beyond a history of violence and live together. Those on opposite sides of Northern Ireland’s sectarian divide may never be friends, Blair says, but if they can stop killing one another and coexist peacefully, so can the citizens of Tel Aviv and Ramallah.

The Rev. Ian Paisley, the longtime fierce opponent of compromise with IRA-linked Sinn Fein who became Northern Ireland’s top official when he and his foes agreed in March to share power, paid Blair an emotional tribute in Britain’s House of Commons on the outgoing leader’s last day in office. Blair’s deep, detailed engagement in a decade of peace talks, he said, had been crucial to securing a settlement in Northern Ireland.

“He’s entered another colossal task,” Paisley said at Blair’s final prime ministerial question-and-answer session last week. “I hope that what happened in Northern Ireland will be repeated and that at the end of the day he’ll be able to look back and say it was well worthwhile.”

The Israeli-Palestinian conflict, though, is even bloodier and more bitter than the troubles that plagued Belfast, and Blair is jumping in at a particularly difficult moment.

Just weeks ago, tensions between Hamas and Fatah broke into open violence in the Palestinian territories, leaving Hamas – regarded by Israel and the West as a party of terrorists – in control of Gaza and the more moderate Fatah in charge in the West Bank.

The turmoil leaves the already dim prospect of a new round of peace talks with Israel even more remote.

And Blair’s baggage is likely to make it difficult for him to fulfill the mission laid out by the so-called “Quartet” of America, the European Union, the United Nations and Russia. The would-be peacemakers want him to focus on boosting Palestinian governance and the territories’ economy, but many experts say he’ll have trouble making progress without being able to simultaneously address grievances against Israel.

While Blair is liked and trusted on the Israeli side, many Palestinians and other Arabs detest him for his role in Iraq and his refusal last year to call for a quick end to Israel’s bombardment of Lebanon, a stance many saw as symbolic of his reluctance to diverge publicly from positions laid down by President Bush.

His caught-on-tape offer to Bush at the 2006 G-8 Summit to travel to the Mideast, where he said he could afford to “just talk,” while a visit by Secretary of State Condoleezza Rice would have to produce concrete results, added to long-standing perception of Blair as overly deferential to the U.S. president.

Both Bush and Blair are widely seen in the Arab world and by many Europeans as biased toward Israel and therefore unable to mediate objectively in the conflict.

Blair has long said that neither the problems of the wider Middle East nor the tensions between the Muslim world and the West could ever be adequately addressed without a resolution to the Israeli-Palestinian conflict, which he sees as an open sore that feeds hatred and extremism in the region.

He’s widely thought to have pushed Bush privately for years to engage more deeply in the peace process, believing that only Washington has the heft to demand real progress. But he had little to show for those efforts as he left his 10 Downing St. office for the last time. Like his old friend Bill Clinton, Blair seems genuinely impassioned about Israeli-Palestinian peace and wanted badly to secure gains there before he stepped down as prime minister. Since announcing his resignation plans last fall, he said repeatedly that he would use his last months in power to push for a settlement. The recent violence and the big step backward it represents were a bitter disappointment.

Also like Clinton, Blair may have hoped a successful peacemaking effort would lend luster to his tainted legacy; instead, his political epitaph is still dominated by the bloody and unpopular mess in Iraq.

He may hope to change that if he can succeed in his new post by laying the groundwork for an eventual resumption of talks. And in many ways, the Mideast role is perfect for him.

Beth Gardiner wrote this article for The Star-Ledger of Newark, N.J.