Jared Kushner, a main architect of the US deal to solve the Palestinian-Israeli conflict, said the Palestinian leadership was making a strategic error by not attending the meeting in Bahrain on a new economic framework that he called crucial to peace.
Mr Kushner, senior adviser and son-in-law to US President Donald Trump, said billions of dollars in aid to the Palestinians had done little to improve their lot or instill good governance.
He invited Palestinians to judge for themselves by watching the proceedings of the Peace to Prosperity meeting in Bahrain, which will be streamed live online.
The economic component of the peace plan was unveiled in Washington on the weekend. It claims it can double regional GDP, create a million jobs, halve poverty and reduce unemployment to 10 per cent.
Mr Kushner said that instead of looking at the merits of the plan, Palestinian leaders had launched a campaign of slogans calling it an abandonment of their cause.
“They were geared to reject anything we put up before they knew what it was," he said. "This is a very strong package. Fighting it instead of embracing it is a strategic mistake."
He said the economic plan was contingent on a peace deal guaranteeing open borders, security and rule of law.
“Without an economic future no political solution could really hold," Mr Kushner said. "Right now you have a status quo that is unsustainable."
He refused to comment on the political aspect of the plan, which is expected to be unveiled after Israel’s election in September.
The Bahrain conference aims to attract $50 billion (Dh183.64bn) to invest in projects in the occupied West Bank, Gaza, Lebanon, Jordan and Egypt.
Few senior regional figures are expected to attend the workshop, although the head of the International Monetary Fund will attend.
Among those betting on the failure of the Trump plan is Iran, which backs Hamas and Islamic Jihad in Gaza.
Mr Kushner said Iran would stand to lose from any normalisation involving Israel.
“Iran is not looking to make the lives of the Palestinians people better," he said.
"A common thread in the past 70 years is that a lot of countries have used hatred of Israel as a way to deflect from a lot of their own shortcomings."
Mr Kushner said most of the Palestinian criticism of the plan has been “more emotional than actually specific”, and ignored the plan’s focus on human development.
“People who have spent the time going through the 140 pages we have produced were pleasantly surprised with the depth and the detail of what we have put out,” he said.
“I believe it is a way to enhance the lives of the Palestinian people.”