Israel’s centrist Blue and White party leader Benny Gantz praised Donald Trump’s Middle East peace plan and said he would help to implement it after his country’s general election.
Mr Gantz, Prime Minister Benjamin Netanyahu's rival for the country's March election, met Mr Trump at the Oval Office on Monday.
"The president's peace plan is a significant and historic milestone," he said after his meeting.
"Immediately after the elections, I will work towards implementing it from within a stable functioning Israeli government, in tandem with the other countries in our region."
Mr Gantz said he and Mr Trump discussed "matters of the utmost importance to Israel's future and security", but he would not disclose the details of the conversation.
Mr Netanyahu, also met Mr Trump on Monday to discuss the plan.
The US president said on Monday that he would reveal the long-delayed Middle East peace proposal on Tuesday and he believes that the Palestinians would eventually endorse it, despite refusing to engage on the subject.
The Palestinians stopped talking to the Trump administration after it recognised Jerusalem as Israel’s capital in December 2017.
The US move was followed only by Guatemala.
Mr Trump will deliver joint remarks with Mr Netanyahu to outline the plan at 5pm GMT on Tuesday.
But it is widely expected to be heavily in favour of Israel and the Palestinians have not been consulted on the political side of the deal.
Mr Netanyahu has hailed the plan as a chance to “make history” in defining Israel’s borders, but it is unclear that it will gain any international support.
The UN and most of the international community have long supported a two-state solution between Palestine and Israel.
Alleged leaks of the plan, denied by Mr Trump, have suggested it could declare settlements in the occupied West Bank legal.
It is unclear if the plan will support Palestinian statehood, but The Jerusalem Post reported it is expected to include annexing all Israeli settlements to Israel, along with most of the Jordan Valley.
During his meeting with Mr Netanyahu in Washington on Monday, Mr Trump said his plan "makes sense for everybody", and said that for Palestinians, "it's something they should want".
"They probably won't want it initially," Mr Trump said. "But I think in the end they will. It's very good for them. In fact, it's overly good to them.
"So we'll see what happens. Now without them, we don't do the deal and that's OK."
Palestinian Prime Minister Mohammad Shtayyeh decried the unpublished plan on Monday.
"We reject it and we demand the international community not be a partner to it because it contradicts the basics of international law and inalienable Palestinian rights," Mr Shtayyeh said.
"It is nothing but a plan to finish off the Palestinian cause.
He told a Cabinet meeting that the political part of the plan was a bid to help Mr Trump and Mr Netanyahu as they faced troubles at home.
The Israeli leader was indicted on charges of corruption and fraud at the end of last year and is struggling to form a government.
Mr Trump, meanwhile, is facing a Senate hearing on his impeachment this week.
The Middle East peace plan has been delayed several times, as Mr Netanyahu failed to form a government after two elections deadlocked with Mr Gantz last year.
Israelis will return to the polls on March 2 for their third election in a year.
The economic part of the Middle East plan was released in June last year but was rejected by the Palestinians.
Jared Kushner, Mr Trump’s adviser and son-in-law who led that part of the plan, likened it to the Marshall Plan to rebuild Western European economies after the Second World War.