MANAMA — Jared Kushner said on Wednesday that the door remained open to the Palestinians to engage in his peace initiative as he accused their leaders of not caring about their own people for rejecting his $50 billion economic framework.

US President Donald Trump's son-in-law launched a long-awaited Middle East initiative with an intimate two-day conference in Bahrain, where economic leaders touted his plan as holding the potential to jump-start the Palestinians' stagnant economy.

Closing the conference at a luxury hotel in the capital Manama, the 38-year-old real estate investor promised to put out the political plan at "the right time" and said the Palestinian Authority could help its people by embracing the US recommendations.

"If they actually want to make their people's lives better, we have now laid out a great framework in which they can engage and try to achieve it," Kushner told reporters.

"We're going to stay optimistic," he said. "We have left the door open the whole time."

He said the Trump administration was trying a fresh approach to the long intractable Middle East conflict and that the authors of the economic framework had not seen the political plan.

"What the leadership has done is that they've blamed Israel and everyone else for all the people's problems, when in fact the common theme coming up is that this is all achievable if the government wants to make these reforms," Kushner said.

The Palestinian Authority boycotted the "Peace to Prosperity" workshop, accusing the unabashedly pro-Israel Trump of dangling the prospect of cash to try to impose political solutions and ignoring a fundamental issue of Israeli occupation.

The "Peace to Prosperity" sets an ambitious goal of creating one million new Palestinian jobs through $50 billion of investment in infrastructure, tourism and education in the territories and Arab neighbors.

Christine Lagarde, the managing director of the International Monetary Fund, praised the plan for focusing on jobs and said "all the goodwill in the world" was needed to prevent a severe deterioration of the Palestinian economy.

"So if there is an economic plan, if there is urgency, it's a question of making sure that the momentum is sustained," Lagarde said.

Tax revenue is being held up in a dispute with Israel, which has blockaded the Gaza Strip for more than a decade because of the Hamas' leadership of the crowded and impoverished territory.