US President Donald Trump’s son-in-law and White House adviser Jared Kushner will brief the UN Security Council about the divisive peace plan to solve the Palestinian-Israeli conflict.
Mr Kushner is the architect of the plan that was three years in the making.
It has been widely viewed as biased towards Israeli and was rejected at the weekend by the Arab League and then the Organisation of Islamic Co-operation.
The plan calls the entirety of Jerusalem inside the security barrier to be handed to Israel, including the Old City that holds the third-holiest site in Islam.
It promises a Palestinian state with a capital in an occupied West Bank village if the Palestinians meet highly difficult conditions.
Mr Kushner's briefing to UN ambassadors comes as a UN draft resolution tabled by Indonesia and Tunisia condemned the plan for approving Israeli annexation of settlements in the occupied West Bank.
The draft text, which will probably be vetoed by the US, offered some members a dim view of the peace plan that Mr Trump revealed last week.
Diplomats said negotiations on the text would probably begin this week.
Palestinian President Mahmoud Abbas is expected to speak to the council next week about the plan, possibly coinciding with a vote on the draft resolution.
The resolution stresses the illegality of annexing any part of occupied Palestinian territories, the draft seen by Reuters says.
While the Palestinians rejected the plan, some Arab governments said it represented a starting point for a renewal of long-stalled negotiations.
The resolution stresses the need for swift international and regional efforts to start credible negotiations on all issues in the Middle East peace process.
A US veto at the council level would allow the Palestinians to take the draft text to the 193-member UN General Assembly, where a vote would publicly show how Mr Trump's peace plan has been received internationally.
Iran's supreme leader Ayatollah Ali Khamenei on Wednesday called the US proposal a sign of Mr Trump's "viciousness and manipulation".
He said the US and Israel would "try to further their plot with bribes, weapons and enticements".
Mr Khamenei said in a tweet that the solution for Palestinians is to engage in "bold resistance" and "force out the Zionist enemy and the US".
"All Muslim nations and the world of Islam must support them too," he said.
The Iranian regime supports the Hamas movement that controls the Gaza Strip and has fought three wars with Israel since 2008.
Iran supplies funds to Hamas and helps it with its rocket arsenal and missile technology.
The US plan calls for Gaza to be demilitarised to prevent rocket fire at Israeli territory.