WASHINGTON — Under the shadow of fresh violence, President Barack Obama convened the first direct Israeli-Palestinian talks in two years Wednesday, challenging Middle East leaders to seize a fleeting opportunity to deliver peace to a region haunted by decades of hostility.

"I am hopeful, cautiously hopeful, but hopeful," Obama said with the leaders of Jordan, Egypt, Israel and the Palestinians beside him in the crowded East Room of the White House. Earlier Obama had met with each individually, and they gathered afterward for dinner.

The mood appeared cordial as the leaders solemnly commenced the talks aimed at creating a sovereign Palestinian state beside a secure Israel. Palestinian President Mahmoud Abbas and Israeli Prime Minsster Benjamin Netanyahu shook hands warmly and thanked Obama for bringing them together despite such intractable differences as Abbas' demand that Israel end settlement expansion in the West Bank.

"Do we have the wisdom and the courage to walk the path of peace?" Obama asked.

In turn, each of the leaders answered positively but with qualifications. And they spoke of hopes for a breakthrough within the one-year timeframe prescribed by Obama.

Netanyahu said his nation desires a lasting peace, not an interlude between wars. He called Abbas "my partner in peace," and said, "Everybody loses if there is no peace."

Abbas urged Israel to freeze settlement construction in areas the Palestinians want as part of their new state, and to end its blockade of Gaza, which is controlled by the militant Hamas movement. The settlements issue is a central obstacle to achieving a permanent peace.

"We will spare no effort and we will work diligently and tirelessly to ensure these negotiations achieve their cause," Abbas said, as translated into English.

Said Jordan's King Abdullah II: "Mr. President, we need your support as a mediator, honest broker and a partner. If hopes are disappointed again, the price of failure will be too high for all."

With the Israelis and Palestinians far apart on key issues, expectations for the Washington talks are low, yet the stakes are high.

Direct Israeli-Palestinian negotiations broke off in December 2008, in the final weeks of the George W. Bush administration. The Obama administration spent its first 20 months in office coaxing the two sides back to the bargaining table.

The Israeli-Palestinian conflict is a constant source of grievance and unrest among Muslims. The failure of past peace efforts has left both sides with rigid demands and public ambivalence about the value of a negotiated settlement.

American officials are hopeful they can get the two sides this week at least to agree to a second round of talks, likely to be held in the second week of September. That could be followed by another meeting among Obama, Netanyahu and Abbas on the sidelines of the U.N. General Assembly near the end of the month in New York.

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 controls Gaza. Hamas is not part of the negotiations and has asserted that talks will be futile. It claimed responsibility for attacks against Israelis Tuesday and Wednesday that killed four and wounded two.

Each of the leaders pledged to work diligently toward peace, but they also made plain that their own national interests must be satisfied.

"We do not seek a temporary respite between outbursts of terror," said Netanyahu. And he stressed the central importance of security assurances for the Jewish state as part of any land-for-peace agreement with the Palestinians.

"We left Lebanon, we got terror. We left Gaza, we got terror. We want to ensure that territory we concede will not be turned into a third Iranian-sponsored terror enclave aimed at the heart of Israel," Netanyahu said. Peace, he added, must "end the conflict between us once and for all."

In earlier remarks Wednesday, Obama emphasized the urgency of making peace, while dampening expectations for a sudden breakthrough. He was adamant that 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 United States is going to be unwavering in its support of Israel's security. And we are going to push back against these kinds of terrorist attacks. And so 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."