– The Associated Press

WASHINGTON – Struggling to break decades of hostility, President Obama convened an ambitious new round of Mideast peace talks Wednesday and told Israeli and Palestinian leaders they faced a fleeting chance to settle deep differences.

“This moment of opportunity may not soon come again,” Obama said at the White House before hosting Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas in the first face-to-face peace talks in nearly two years. “They cannot afford to let it slip away.”

Obama sought to temper expectations, noting that it had taken his administration this long just to get the two sides back to the bargaining table for talks aimed at creating a sovereign Palestinian state beside a secure Israel.

“The hard work is only beginning,” Obama said, with Secretary of State Hillary Rodham Clinton and special Mideast peace envoy George Mitchell, a former senator from Maine, at his side. “Neither success nor failure is inevitable,” Obama said, “but this much we know: If we do not make the attempt, then failure is guaranteed. If both sides do not commit to these talks in earnest, then long-standing conflict will only continue to fester and consume another generation, and this we simply cannot allow.”

He made clear that the stakes are high.

“Too much blood has already been shed. Too many lives have already been lost. Too many hearts have already been broken,” he said. “And despite what the cynics say, history teaches us that there is a different path. It is the path of resolve and determination, where compromise is possible and old conflicts at long last can end.”

In a carefully arranged series of talks designed to lay the final groundwork for negotiations, Obama met separately with Netanyahu and Abbas as well as with Jordan’s King Abdullah II and Egyptian President Hosni Mubarak. Later they all gathered for dinner, a private prelude to today’s scheduled start of formal negotiations at the State Department.

In earlier remarks after his meeting with Netanyahu, Obama assailed those responsible for the killings of four Israelis near the West Bank city of Hebron on Tuesday. The militant Hamas movement, which rejects Israel’s right to exist and opposes peace talks, claimed responsibility.

Direct Israeli-Palestinian negotiations broke off nearly two years ago, in December 2008, and the Obama administration spent its first 20 months in office coaxing the two sides back to negotiations. Obama was adamant Wednesday that extremist violence would not derail the process.

“There are going to be extremists and rejectionists who, rather than seeking peace, are going to be seeking destruction,” he said. “The message should go out to Hamas and everyone else who is taking credit for these heinous crimes that this is not going to stop us.”

Expectations for the Washington talks are low, yet the consequences of failure are high. The Israeli-Palestinian conflict is a constant source of grievance and unrest in the Muslim world. The failure of past peace efforts has left both sides with rigid demands and public ambivalence about the value of a negotiated settlement.

Under a so-called two-state solution to the Israeli-Palestinian conflict, the West Bank is supposed to make up the bulk of an independent Palestinian state alongside Israel, with precise borders to be drawn at the peace table. Expansion of Jewish housing makes those borders ever more complicated.

Beyond the settlements, Israel and the Palestinians face numerous hurdles in resolving other contentious issues, notably the borders of a future Palestinian state, the political status of Jerusalem and the fate of Palestinian refugees.

Also complicating the outlook are internal Palestinian divisions that have led to a split between Abbas’ West Bank-based administration and Hamas, which is in control of Gaza. Hamas is not part of the negotiations and has asserted that talks will be futile.