During a news conference with Palestinian President Mahmoud Abbas, President Trump said that his administration will work hard to facilitate a peace deal between Israel and the Palestinians. (The Washington Post)

President Trump on Wednesday expressed confidence that he can help the Israelis and the Palestinians negotiate a peace agreement, declaring as he stood next to Palestinian President Mahmoud Abbas at the White House that “we will get this done.”

But despite expressing optimism in the face of the long odds and an increasingly fraught relationship between the two Middle East players, Trump also warned that “there can be no lasting peace unless the Palestinian leaders speak in a unified voice” and renounce violence and hate — a reference to the split between the Palestinian Authority, which controls the West Bank, and the militant Hamas group, which controls the Gaza Strip.

Trump also cast the United States in a more intermediary role.

“I’m committed to working with Israel and the Palestinians to reach an agreement, but any agreement cannot be imposed by the United States or any other nation,” he said. “The Palestinians and Israelis must work together to reach an agreement that allows both peoples to live, worship and thrive and prosper in peace. And I will do whatever is necessary to facilitate the agreement, to mediate, to arbitrate anything they’d like to do, but I would be a mediator or an arbitrator or a facilitator.”

Abbas nodded to the president's background as a businessman, saying he respected Trump's “great negotiating ability,” and called for a two-state solution. When Israeli Prime Minister Benjamin Netanyahu visited the White House earlier this year, Trump expressed support for either a one- or two-state solution, saying that he “could live with” either and that he wanted the outcome “that both parties want.”

“Our strategic option, our strategic choice, is to bring about peace based on the vision of the two-state, a Palestinian state, with its capital in East Jerusalem, that lives in peace and stability with the state of Israel, based on the borders of 1967,” Abbas said.

The Trump administration has yet to articulate a clear strategy for how it will engage in any negotiations between the Israelis and the Palestinians with analysts warning that the prospects for peace remain dim.

Asked Wednesday afternoon why Trump might succeed at a task where his predecessors have not, White House press secretary Sean Spicer said: “I think the man is different. The president’s diplomacy style is paying dividends.”

Spicer said that Trump, still early in his presidency, had forged personal bonds with a range of foreign leaders.

“This president’s style is one to develop a personal bond with individuals,” Spicer said.

Robert Danin, a senior fellow at the Council on Foreign Relations and a former senior State Department official, said he found Wednesday's events at the White House striking.

“It was completely lacking in any sense of how, what the path forward is, what it is about,” Danin said, referring to Trump’s plan for negotiating with the two parties. “It almost assumed it’s just about the Israelis and the Palestinians working it out and doing the ultimate deal.”

Danin added that the situation is far more complicated than Trump seems to understand.

“The way President Trump talks about this issue is as if it’s just this negotiation between the Israelis and the Palestinians, and if we can just negotiate it right and effectively, and with Trump as the new dealmaker, we can succeed where others haven’t before,” he said. “This just flies in the view of many analysts who just feel that this approach has not succeeded for a reason and it is not just a function of bad dealmaking or negotiations.”

Finding a solution to the decades of deep tensions between Israelis and Palestinians has bedeviled many of Trump's predecessors in the White House, but on Wednesday, the president said he is game for the challenge.

“Over the course of my lifetime, I’ve always heard that perhaps the toughest deal to make is the deal between the Israelis and the Palestinians. Let’s see if we can prove them wrong, okay?” he said.

Abbas and a small entourage arrived outside the West Wing in a black limousine shortly before noon and were greeted by Trump. The Palestinian leader and his advisers are weighing efforts to restart peace negotiations with Israel with the aim of securing Palestinian borders, a capital and a state.

“It is a great honor to have the president with us,” Trump said after taking Abbas into the Oval Office. “We are going to have lunch; we are going to have discussions.”

Trump, who in February met with Netanyahu at the White House, has called a possible Palestinian-Israeli accord “the toughest deal in the world” but one he is determined to try to broker. Some analysts are skeptical, however, that Trump will succeed in an arena where his predecessors have fallen short.

“Every president, when they come into office, thinks they can bring about an Israel-Palestinian deal,” said James Gelvin, professor of modern Middle Eastern history at the University of California at Los Angeles. “Everyone fails, and then they turn their attention to issues that are more pressing. This is probably going to be the same sort of thing.”

Dennis A. Ross, a counselor at the Washington Institute for Near East Policy and a former American envoy to the Middle East, said that although immediate results are unlikely, the meetings could set the stage for later progress.

“You can’t solve the conflict right now. The gaps between the Israelis and Palestinians are too wide. We are at the lowest ebb in Israeli-Palestinian perceptions of each other since I’ve been working on this,” Ross said. “But you can create a sense of possibility, you can break the stalemate, you can show that something is possible. And that’s what I think can happen here — you can show that a sense of possibility exists.”

Abbas, 82, arrived in Washington as a weakened political figure. Unpopular among his own people, there are questions about his legitimacy as leader of the Palestinian Authority.

Trump has spoken with Abbas by phone, but their White House meeting is their first face-to-face encounter.

Among other challenges, the Republican president is facing pressure from members of his party to demand that the Palestinian Authority end financial payments to the families of Palestinians who commit violence against Israelis. A group of Republican senators has introduced legislation to cut off American aid if that demand isn't met.

“I think the thrust of the meeting will be on one hand prepared to work with making clear what they expect from him,” Ross said.

Ross said the meeting is important to Abbas because it elevates him in the eyes of other Middle East leaders. “The administration is basically making him relevant, and they’re making him relevant at a time when all of the Sunni Arab leaders want to make sure the Trump administration won’t withdraw from the region,” Ross said.

During Trump’s meeting with Netanyahu in February, administration officials pushed for restraint on the expansion of Jewish settlements in the West Bank on land the Palestinians want for a future state. Those talks ended with no firm agreement. About 400,000 Jewish settlers are living in the West Bank, which is known by its ancient names of Judea and Samaria by many Israelis.

Trump, who campaigned for president as an unwavering ally of Israel, has sounded an optimistic note about ending the generations-old dispute between the Israelis and the Palestinians. “I want to see peace with Israel and the Palestinians,” Trump said in an interview last week with the Reuters news agency. “There is no reason there’s not peace between Israel and the Palestinians — none whatsoever.”

Trump sent his new Middle East envoy, former real estate lawyer Jason Greenblatt, to Jerusalem and Ramallah in March to explore the possibilities of a U.S. role in a peace process. The visit appeared to be well received by both sides. Trump also named his son-in-law, Jared Kushner, as his point man for peace efforts in the Middle East.

The Obama administration's peace attempts ultimately bore no fruit. Nine months of peace talks under then-Secretary of State John F. Kerry broke down amid bitter recriminations by Israelis and Palestinians in April 2014.

Since then, there has been a spike in violence by lone-wolf-style Palestinian assailants, leading to tough countermeasures by Israeli security forces.

“Abbas has hitched his horse for a long time to the Americans and a negotiated settlement, and so he really wants to deliver,” Gelvin said. “The problem is: He doesn’t really have a partner in order to be able to deliver. The Israelis are not anxious to deliver.”

Wednesday’s visit lacked much of the pomp of previous visits by world leaders. Rather than hold a full-blown news conference, Abbas and Trump were planning to make a joint statement during the visit. Abbas, who is not known for his oratory, typically does not hold news conferences.

Abbas was also set to hold a separate meeting later Wednesday with Secretary of State Rex Tillerson, officials said.

During Netanyahu’s White House visit in February, Trump both flattered and pressured him when the two fielded questions from journalists. During that visit, Trump made headlines by saying he “could live with” either a separate Palestinian state or a single state as a peaceful outcome.

“I want the one that both parties want,” Trump said.

William Booth in Jerusalem and Carol Morello in Washington contributed to this report.