DEAD SEA, Jordan - Hoping to use economic promise as a bridge to a peace deal between Palestinians and Israel, Secretary of State John Kerry announced an estimated $4 billion economic development proposal for the West Bank on Sunday that he said could cut the 21 percent unemployment rate by two-thirds.

"The greatest existential threat and the greatest economic threat to both sides is the lack of peace," Kerry said. "To not try to head these off would be tragic, and it would be irresponsible."

International business leaders rallied by former British Prime Minister Tony Blair will propose new agricultural, construction, and other investment to the Palestinian Authority that could increase the Palestinian gross domestic product by 50 percent over three years, Kerry said.

The State Department would not identify participating companies or provide other details about the content or timing of individual proposed investments.

Kerry addressed a World Economic Forum meeting after speeches by Palestinian Authority President Mahmoud Abbas and Israeli President Shimon Peres. The gathering on the shores of the Dead Sea in Jordan was a rare direct meeting between Israeli and Palestinian leaders, although Israeli Prime Minister Benjamin Netanyahu did not attend.

Improving lives and expectations for Palestinians, many of them young and underemployed, is key, Kerry said, to building an independent Palestinian state at peace with neighboring Israel, and there is no time to waste.

Kerry offered no specifics on the program, but said it would focus on jobs and tourism. Blair and Kerry friend Tim Collins, a billionaire investor, recruited business leaders over the past six weeks as Kerry tried to nudge the two sides back to direct peace talks that have been mostly stalled for five years.

"Negotiations can't succeed if you don't negotiate," Kerry said Sunday.

Peres and Abbas thanked Kerry for his efforts and pledged willingness to make peace.

"I have an agreement here which you both can come up and sign," Kerry joked. "We'll get there, we'll get there."

Kerry has made restarting peace talks the main objective of his tenure as secretary of state, devoting much of the past three months to preparations that ask both sides to make good-faith concessions that would improve the atmosphere for talks. He said last week that his goal is talks without any preconditions - which he called the bane of past attempts.

Peres made a direct invitation to Abbas, calling him Israel's partner for peace.

Abbas delivered a largely unyielding address, which accused Israel of failing to seize the opportunity for peace presented by the 2002 Arab Peace Initiative that Kerry is now using as a basis for new talks.

Abbas appeared to remain skeptical of Israel's intentions. He repeated that Palestinians will not accept "economic solutions" as a replacement for a free and sovereign country, nor would they accept "a temporary state, with temporary borders," where Israel agrees to borders for 50 percent of Palestine with a promise to revisit the issue in 15 years.

"Let us put an end to illusions," Abbas said. "Just forget it. Forget it."

Peres said he would not argue with Abbas nor debate the details from the stage. "President Abbas, you are our partner, and we are yours," he said. He said all their differences are deeply moving and important, but he called on Abbas to sit down with the Israelis and negotiate. "You will be surprised how much can be achieved," he said.

Peres applauded Kerry's economic ideas as "imaginative," but agreed with Abbas that they were not a replacement for peace negotiations.

Abbas praised the Arab Peace Initiative. Introduced in 2002 by Saudi Arabia and endorsed again recently by Arab diplomats, the Arab League proposal offers Israel full recognition and normalization with all Arab nations in exchange for Israel withdrawing to its 1967 borders, including pulling out of East Jerusalem, and "just settlement" for Palestinian refugees who wish to return home to live in peace or receive compensation.