Washington (CNN) President Donald Trump's fragile political standing among American voters may be about to cause dangerous reverberations in the Middle East, even provoking the Pope to express concern.

His announcement Wednesday that he will recognize Jerusalem as the capital of Israel and begin to relocate the US embassy there from Tel Aviv is sparking debate over what the President personally, and the United States, will gain given that the decision marks a sharp foreign policy turn and comes with such high risks.

Critics doubt that the President is acting on the basis of long-held principles or a coherent national security strategy and charge he is instead determined to further personal goals at a time when he needs to show his political base that he is rapidly ticking off his campaign promises.

The question is especially acute because there are so many potential downsides. There are fears Trump's action will trigger violence against Americans and US interests and a wider Middle East conflagration, especially in countries where leaders support the US government. The US Consulate in Jerusalem warned Americans to be wary of demonstrations after Palestinian factions called for "three days of rage" across the West Bank.

Pope Francis voiced "profound concern" over the move, making a "heartfelt appeal to make everyone's commitment to respect the status quo of the city, in accordance with the relevant United Nations resolutions."

Trump's decision also will defy explicit appeals from allied leaders in the Middle East and Europe and could therefore damage American foreign policy goals and relationships. The move is likely to squander any remaining idea that the United States can be an honest broker in the stalled final status talks between Israel and the Palestinians. It is also likely to squelch son-in-law Jared Kushner's attempt to revive the Israeli-Palestinian dialogue.

Given unequivocal criticism by Saudi Arabia on Tuesday, it could also slow another Kushner project -- rapidly warming US ties with the kingdom -- and make it harder for the Saudis to line up publicly alongside Israel in the nascent US policy effort to form a new anti-Iran coalition.

As Aaron David Miller, a former Middle East peace negotiator for Republican and Democratic presidents, warned on CNN: "Jerusalem is a tinderbox, waiting for a match."

Why do it?

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So why would Trump risk providing that spark with a move that seems to come with such potentially unpredictable and dire consequences, especially as he will be blamed if he sends Middle Eastern tensions soaring?

Given Trump's approval rating -- which a poll put at 35% on Tuesday -- and intense focus on honoring campaign promises during a fraught year, many observers sense a political motivation.

CNN's Kevin Liptak reported on Tuesday that the President was concerned about losing his base and has taken steps to galvanize conservative support -- for instance, in his endorsement of Senate candidate Roy Moore of Alabama, who has been accused of initiating sexual contact with a 14-year-old, sexually assaulting a 16-year-old and pursuing relationships with teenage girls while he was in his 30s. He has denied those claims. The Jerusalem decision also comes with Trump under heavy political pressure as the Russia probe reaches directly into his inner circle

The vow to move the US embassy to Jerusalem was a staple of Trump's campaign speeches, and it appealed to evangelical voters, rich Republican donors and GOP foreign policy hawks.

"When I become President, the days of treating Israel like a second class citizen will end, on Day 1," Trump told the American Israel Public Affairs Committee conference last year.

"We will move the American embassy to the eternal capital of the Jewish people, Jerusalem."

While the risk of moving the embassy appalls his critics, it would not be out of character if the sense of uncertainty appeals to Trump. The President's self image and his appeal to many supporters rests on the idea that he has the courage to take steps other Presidents wouldn't and that he will be unpredictable, disdain political correctness and shatter taboos that defied his predecessors.

"The President has delivered on another major campaign promise," Norm Coleman, the national chairman of the Republican Jewish Coalition, said in a statement on Tuesday. "President Trump is doing what he does so well: recognizing the reality on the ground. No more false news -- Jerusalem is Israel's capital."

Siding with one of his closest friends among foreign leaders, Israeli Prime Minister Benjamin Netanyahu, who backed him in the US election, may also appeal to Trump. His decision will also allow him to defy establishment foreign policy figures and project a tough guy image in the Middle East, one of the world's roughest regions.

US law recognizes Jerusalem

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Of course, Trump might simply believe that he is doing the right thing. After all, US law recognizes Jerusalem as Israel's capital already and there is bipartisan support for the embassy move -- though mostly as part of a final settlement between Israel and the Palestinians, not as a unilateral act.

Senior administration officials said Tuesday that the President was simply making a "recognition of reality" with his action on Wednesday and rejected the idea that he was putting peace moves at risk.

"It seems clear now that the physical location of the American embassy is not material to a peace deal. It's not an impediment to peace and it's not a facilitator to peace," one senior administration official said.

American presidents have for more than two decades used a waiver every six months to forestall the embassy move, partly out of fears that it could set off widespread violence and instability throughout the region. Trump will also sign a waiver on Wednesday -- but on the rationale that it will take years to build and appoint a new US embassy.

Arguments that Trump's move does not have a political dimension, however, are undercut by the evidence of his personality and record so far in office.

Trump has rushed to implement campaign pledges -- for instance, with his Muslim travel ban and his moves against undocumented migrants, which electrified his base and powered his populist campaign crusade in 2016 -- often without much concern for the human consequences for those involved.

And several crucial foreign policy decisions seem as much motivated by personal animosity or preference as detailed foreign policy arguments.

For instance, his refusal to certify the Iran nuclear deal this year flew in the face of facts that said Tehran was complying, but followed multiple reports detailing his personal antipathy to the agreement.

Trump also defied a storm of appeals from foreign leaders not to isolate the United States from the Paris climate accord -- he did so anyway, after frequently blasting global warming as a hoax on the campaign trail.

"As in the case of the Iran nuclear agreement, ideology and political concerns are triumphing over the commonsense recommendations of US and Israeli security experts and the opinion of the majority of Jewish Americans," the liberal, pro-Israel advocacy group J Street said in a statement Tuesday.