It's the most concentrated stretch of presidential comforting to occur during Trump's tenure, which has been marked more by stoking of divisions than displays of empathy. Nevertheless, Trump on Monday hewed to presidential precedent, striking a unifying sentiment during a solemn address at the White House.

"Our unity cannot be shattered by evil, our bonds cannot be broken by violence," Trump said. "And though we feel such great anger at the senseless murder of our fellow citizens, it is our love that defines us today -- and always will, forever."

His aides expect the two-day stretch to prove emotionally taxing for the President, who has yet to confront the type of devastation seen in Puerto Rico or Las Vegas since taking office in January. White House officials initially considered canceling his trip to Puerto Rico after the Nevada shooting but ultimately determined he should still travel there.

During dark national moments, US presidents often turn away from divisive political rhetoric in a bid to console Americans and project a sense that the country's citizens share a common bond. Sometimes that includes delivering eulogies or attending memorial services for victims, or assessing damage after a major natural disaster.

Comforting Americans at what is often the worst moment of their life is a skill that takes time for presidents to develop, and exacts an emotional toll, past holders of the job say.

Trump has assumed the task at various moments during his first eight months in office. But his trips on Tuesday and Wednesday amount to the weightiest tests yet of his ability to project both sadness and resolve, and a gauge of his willingness to drop the bombastic political rhetoric that he's injected into nearly every situation since becoming president.

Puerto Rico

JUST WATCHED Cuomo: Puerto Ricans can't be lying about aid Replay More Videos ... MUST WATCH Cuomo: Puerto Ricans can't be lying about aid 02:05

Trump landed in Puerto Rico having provoked a spat with the mayor of the island's capital city over disaster relief efforts, which the President insists are proceeding without fail. He repeated his praise of the federal recovery operation on Monday.

"We are going to be seeing all of the first responders, the military, FEMA, and frankly, most importantly, we are going to be seeing the people of Puerto Rico," Trump said in the Oval Office ahead of talks with the Thai prime minister. "It's been amazing what's been done in a very short period of time on Puerto Rico. There's never been a piece of land that we've known that was so devastated."

The US territory remains debilitated following the hurricane, with water and fuel still scarce and the majority of the island without power. Trump reacted harshly over the weekend to comments from San Juan Mayor Carmen Yulín Cruz suggesting the island was still lacking in robust federal aid.

"Such poor leadership ability by the mayor of San Juan, and others in Puerto Rico, who are not able to get their workers to help," Trump tweeted on Saturday morning. "They want everything to be done for them when it should be a community effort."

Other administration officials suggested Cruz had refused invitations to participate in FEMA briefings, opting instead to appear on television. The mayor, in turn, insisted in an interview with CNN that she would not be distracted by "small comments, by politics, by petty issues."

"Well I think she's come back a long way," Trump said before he left for Puerto Rico. "I think it's now acknowledged what a great job we've done. And people are looking at that. In Texas and in Florida, we get an A-plus. I think we've done just as good in Puerto Rico and it's actually a much tougher situation ... Whether it's her or anybody else, they're all starting to say it."

The sour public dispute reflected a sharp break from how past presidents have reacted to criticism of their attentiveness during a natural disaster. President George W. Bush was excoriated for his response to Hurricane Katrina in 2005, which included what in retrospect was misplaced praise for his FEMA director.

But Bush did not lash out at infuriated local officials when they pleaded with the federal government for more assistance.

In responding to a series of hurricanes that made landfall in the United States, Trump and his aides have been cognizant of avoiding the pitfalls faced by predecessors in dealing with natural disasters. Trump made quick visits to Texas and Florida after storms damaged parts of those states and sought to project a display of federal competence. He was cautious about appearing overly valedictory before the full scope of the recovery could be gauged.

In Puerto Rico, however, the President has shown little regard for presidential custom. Aside from his fight with San Juan's mayor, Trump has openly lauded his government's response, despite the evident shortfalls on the island.

"We have done a great job with the almost impossible situation in Puerto Rico," he tweeted this weekend. "Outside of the Fake News or politically motivated ingrates, people are now starting to recognize the amazing work that has been done by FEMA and our great Military."

We have done a great job with the almost impossible situation in Puerto Rico. Outside of the Fake News or politically motivated ingrates,... — Donald J. Trump (@realDonaldTrump) October 1, 2017

Trump on Tuesday is meeting with local officials about the recovery efforts and view damaged areas of the island.

"I expect the focus to be on the recovery efforts, which we're fully committed to," Sanders said. "The top priority for the federal government is certainly to protect the lives and the safety of those in affected areas, and provide life-sustaining services as we work together to rebuild their lives."

Deadliest mass shooting in modern US history

JUST WATCHED Obama sings 'Amazing Grace' during eulogy for pastor Replay More Videos ... MUST WATCH Obama sings 'Amazing Grace' during eulogy for pastor 01:44

In Las Vegas on Wednesday, Trump confronts a separate tragedy after a gunman rained bullets on a country music festival, killing more than 50. He announced he would travel there during his morning statement from the White House.

"It's a very sad moment for me, for everybody," Trump said. "For everybody, no matter where you are, no matter what your thought process, this is a very, very sad day."

Presidents have confronted American mass shootings differently as they have become more common over the past two decades. President Barack Obama, over the course of his two terms, evolved from expressing feelings of sadness and anger, to resolve at enacting new gun controls, to -- at the end of his tenure -- resignation that the country's political leaders lacked the will to make meaningful changes.

Speaking at a eulogy for a slain pastor after the Charleston, South Carolina, church shooting, Obama broke into strains of "Amazing Grace" -- a raw display of emotion that encapsulated the country's grief.

Trump has yet to demonstrate that type of sentiment as president. Trump's first public remarks about the Las Vegas shooting were uncharacteristically subdued. He initially did not speak about the gunman, who authorities identified as 64-year-old Stephen Paddock, though he referred to him on Tuesday as a "very, very sick individual."

And he avoided discussion of gun control , even as Democrats and activists insisted lawmakers in Washington confront again the widespread availability of assault weapons. He didn't answer reporters' questions on Tuesday about whether the shooting was an act of domestic terrorism.

Instead, Trump has used broader language to acknowledge the anxiety and senselessness surrounding the attack.

"Even the most terrible despair can be illuminated by a single ray of hope," he said Monday.

It was a different tone from the one Trump adopted after mass shootings that occurred while he was running for president last year. After gun attacks in San Bernardino, California, and Orlando, Trump used the moment to harden his position on radical Islamic terrorism.

Unlike the San Bernardino or Orlando incidents -- both carried out by Muslim-Americans -- the perpetrator of the Las Vegas shooting was an older white male. At the White House on Monday, Sanders said it was too early to determine whether the incident amounted to domestic terrorism.

And she ascribed Trump's more muted tone after Las Vegas to his elevated standing.

"I think there's a difference between being a candidate and being the President," she said.