"It's a great plan. It's a plan that really would work," Trump told reporters on Air Force One en route to a Republican Party meeting in Florida.
The plan, which would be rolled out as Trump's Senate impeachment trial continues on Capitol Hill, is expected to be pro-Israel, which would please U.S. evangelical and Jewish voters. It also comes as Netanyahu seeks immunity from Israeli lawmakers from charges stemming from corruption investigations.
Trump said he was surprised that both Netanyahu and Gantz were willing to take a break from campaigning for the March 2 elections to join him Tuesday in Washington.
"They both would like to do the deal. They want to see peace," Trump said. "Look, Israel wants peace, Palestinians want peace. They all want peace. Not everyone wants to say it."
He said his administration has talked briefly to the Palestinians, who have rejected the administration's peace plan before it even comes out.
"We've spoken to them briefly. But we will speak to them in a period of time," Trump said. "And they have a lot of incentive to do it. I'm sure they maybe will react negatively at first, but it's actually very positive to them."
"We took away their money," Trump added. "That's a lot of money for them."
The U.S. stopped funding the U.N. agency that helps Palestinian refugees, which slashed hundreds of millions of dollars in aid for projects in the West Bank and Gaza and cut funding to hospitals in Jerusalem that serve Palestinians. Trump also closed the Palestinian diplomatic mission in Washington, saying the Palestinians refused to engage in peace talks with Israel.
Vice President Mike Pence announced the invitation for Netanyahu and Gantz to visit during a meeting with the prime minister in Jerusalem after addressing an international forum Thursday on the Holocaust. He said that at Netanyahu's request, the invitation was also issued to Gantz.
Asked when he would release the plan, which has been shepherded by the president's adviser and son-in-law Jared Kushner, Trump said it would be rolled out "sometime prior" to his meeting with Netanyahu and Gantz. "Probably we'll release it a little bit prior to that."
The plan is expected to strongly favor Israel, and is unlikely to garner any international support if it is seen as undermining the prospect of a two-state solution.
"We have had no better friend than President Trump," Netanyahu said. "With this invitation, I think that the president is seeking to give Israel the peace and security that it deserves."
The Palestinians rejected Trump's peace efforts after he recognized disputed Jerusalem as the capital of Israel and moved the U.S. Embassy there in May 2018. The Palestinians want east Jerusalem, which Israel occupied in the 1967 war and annexed, to be their capital.
"If this deal is announced with these rejected formulas, the leadership will announce a series of measures in which we safeguard our legitimate rights, and we will demand Israel assume its full responsibilities as an occupying power," said Nabil Abu Rdeneh, a spokesman for Palestinian President Mahmoud Abbas.
He appeared to be referring to oft-repeated threats to dissolve the Palestinian Authority, which has limited autonomy in parts of the Israeli-occupied West Bank. That would force Israel to resume responsibility for providing basic services to millions of Palestinians.
"We warn Israel and the U.S. administration from crossing the red lines," Abu Rdeneh said.
Israel's Channel 12 TV, citing Israeli officials, said the plan is expected to be extremely favorable toward Israel and offer it control over large parts of the occupied West Bank. The Palestinians seek the entire territory, which was also captured by Israel in 1967, as the heartland of a future independent state. Most of the international community supports the Palestinian position.
Netanyahu has said he plans to annex the Jordan Valley as well as Jewish settlements across the West Bank, which would all but extinguish any possibility of creating a viable Palestinian state.
Netanyahu has tried to make that the cornerstone of his campaign for reelection following unprecedented back-to-back elections last year that left him in a virtual tie with Gantz, with neither able to cobble together a ruling coalition.
The deadlock was deepened by Netanyahu's indictment last year on serious charges of bribery, fraud and breach of trust stemming from three long-running corruption investigations. Netanyahu has asked Israel's parliament to grant him immunity.
Next week's meeting could produce an awkward scene. Gantz has made Netanyahu's indictment the focus of his campaign to oust the prime minister. And his Blue and White party is leading an effort in parliament to block Netanyahu's immunity request before the election. At the same time, they will be joined by an impeached president who is being tried in the Senate.
The U.S. was believed to be holding back on releasing the peace plan until Israel had a permanent government. Those calculations may have changed as the deadlock in Israeli politics looks to be further prolonged.
Trump may also be looking for a boost from evangelical and pro-Israel supporters as the Senate weighs whether to remove him from office after he was impeached last month, and as he gears up for a reelection battle this year.
Pence was among dozens of world leaders in Jerusalem on Thursday for the World Holocaust Forum. Many of the participants, including Russian President Vladimir Putin and French President Emmanuel Macron, also paid visits to the Palestinians in the West Bank. A Palestinian official said Abbas asked the visiting French and Russian presidents to support the Palestinian position when the plan is published.
"He asked them to refuse and act against any Israeli annexation of Palestinian lands," said the official, speaking on condition of anonymity because he was discussing closed meetings.
While the plan is expected to be friendly to Israel, it could still face opposition from Netanyahu's hard-line partners.
Defense Minister Naftali Bennett, leader of the ultra-nationalist Yamina party, called Trump a "true friend" of Israel and said the country likely stands before a "historic opportunity." But he said his party would not allow the transfer of any land to Palestinian control or for a Palestinian state to be established.
In Washington, Jeremy Ben-Ami, president of the liberal advocacy group J Street, said Trump's plan to address the Israeli-Palestinian conflict won't be a peace plan, "but rather a plan to enshrine the Israeli settler movement's agenda" as U.S. foreign policy.
"It's clear that a U.S. proposal which endorses settlement expansion or annexation does not reflect the true interests of the United States and will not hold as U.S. policy under future administrations," said Ben-Ami, whose organization supports a two-state solution to the conflict.