WASHINGTON — Like so much else in President Trump’s life, it was a decision shaped by financial considerations and, in the end, the hotel business.

Mr. Trump’s abrupt cancellation of the Republican National Convention in Jacksonville, Fla. — a big celebration in a battleground state that he hoped would buoy his re-election campaign — surprised some allies, donors and even aides who weren’t expecting the announcement then, which he attributed to Florida’s soaring rate of coronavirus cases.

But the timing of Mr. Trump’s decision on Thursday night was influenced by the imminent need for the Republican Party to book an enormous number of hotel rooms in Jacksonville and sign other costly service agreements, according to multiple Republicans familiar with the plans. The looming deadline for attendees to make deposits on hotel rooms was next Monday, according to a copy of instructions mailed to delegates.

If party officials proceeded to make those reservations and cancel them later, people familiar with the planning said, it would have added financial losses to an already expensive fiasco involving two cities — Jacksonville and Charlotte, N.C., where the convention was originally set — and two sets of donors raising money in both places.

There were other urgent factors involved in the decision, including the health of party officials and delegates coming from across the country, and Mr. Trump’s sinking political standing, which was largely attributable to months of inattentiveness to the virus. It had become increasingly apparent in recent days that Jacksonville organizers were facing open resistance from local officials and that the city’s Republican mayor, Lenny Curry, once a champion of the convention, was too tied up with virus concerns to cheerlead much for it.

Faced with all that tumult, Mr. Trump chose instead to cancel the convention in an effort to cast himself as putting safety first.

But many of Mr. Trump’s top political advisers had already become convinced that the convention stood a better chance of generating embarrassing news stories — like his recent, unsuccessful rally in Tulsa, Okla. — than a bounce in the polls. In a series of recent conversations with Mr. Trump, they made it clear that he could still pull out, with minimal repercussions, according to people familiar with the discussions.

In the White House on Friday, officials were already mapping out how to generate the political momentum they were hoping to receive after three nights of speeches in Jacksonville. One senior official said internal data showed that the most movable voters were network morning show viewers, and that the next 100 days would involve a heavy media strategy, with Mr. Trump doing more interviews on network morning shows, as well as Sunday shows, while still prioritizing interviews on Fox News.

The party on Friday was also looking for a new location where it could build a stage and host some of the planned convention programming, including Mr. Trump’s acceptance speech on Aug. 27, which he still plans to give.

Another White House official warned that the events would be significantly scaled back from what had been planned for Jacksonville, but that the schedule for officials with speaking slots over the course of the convention would most likely not change.

The cancellation of the convention was a reversal that Mr. Trump only recently settled on. But it was an exit strategy that many of his top advisers had been keeping as an option.

Since moving the convention to Jacksonville from Charlotte in June, Republican officials held off on executing contracts with the city and the convention venue, leaving themselves flexibility to pull out. Mark Meadows, the White House chief of staff, had been advising Mr. Trump that he should move forward as though he was going to have a convention, while leaving himself an off ramp.

State Senator Rob Bradley, a Republican member of the R.N.C. host committee in Jacksonville, acknowledged on Friday that organizers were facing deadlines from major vendors, including hotels.

“It was reaching the point where calls needed to be made so that people could plan accordingly and that financial obligations would not be secured that couldn’t be met from vendors,” he said in an interview.

Last weekend, with those deadlines looming, and with local officials warning they did not have the resources to provide adequate security for the event, top campaign officials decided to brief the president one more time on his options, emphasizing his ability to walk away, people familiar with the discussions said.

Ronna McDaniel, the chairwoman of the Republican National Committee; Bill Stepien, the Trump campaign manager; and Jason Miller, the campaign’s chief strategist, maintained a public position of supporting whatever Mr. Trump chose to do, and cheerfully proclaiming that the show would go on.

But most of the president’s top political advisers, worried that the safety risks from the virus could cause the event to backfire, were in favor of canceling the entire four-day affair in Florida. (The first day’s events are being held in Charlotte.)

Inside the White House, there has been growing skepticism that any large-scale gathering could work, given the rise in coronavirus cases. Fueling those concerns were memories of the campaign’s disastrous rally in Tulsa, where Mr. Trump and his aides hyped the turnout only to find themselves speaking in front of an arena that was two-thirds empty. News that several campaign staff members had tested positive for the virus in Tulsa only added to the negative impression the rally created.

Aides have instead been trying to get Mr. Trump excited about tele-town halls, showing him that he could reach tens of thousands of people in a particular region without forcing them to leave their homes.

As the prospect of canceling the convention looked more and more likely to the small group of aides clued in, over the past few days, one White House official raised the question of sending inconsistent messages, asking how the president could continue pushing for schools to reopen if he was backing down from holding his own convention. Other aides, however, said opening schools was essential, and a mass gathering of Trump supporters — the majority of whom would be over 50 — was not, the people familiar with the discussions said.

Mr. Trump, officials said, was leaning toward changing his mind by Wednesday. That night, Ms. McDaniel, Mr. Stepien and Mr. Miller had a follow-up conversation among themselves and agreed that it seemed likely that the president would decide to shut it down after all, and began preparing for that outcome. But many of them have been operating in Mr. Trump’s orbit long enough to know that nothing is settled until the president himself makes his decision public.

For weeks, as the pandemic continued to spike in Florida, aides had presented Mr. Trump alternative scenarios. One plan discussed, according to someone involved in the conversations, was having three nights of the convention take place in different cities: the first lady, Melania Trump, would speak from Houston; Vice President Mike Pence would address a crowd in his home state, Indiana; and only Mr. Trump’s speech would take place in Jacksonville.

Proponents of that plan said a roving convention could have been spun as a powerful message about the country reopening everywhere, with the bonus of avoiding a single large crowd gathering together for four full days in one city.

How the two parties were approaching their conventions had become a litmus test for their views of the pandemic over all. Focusing on safety, Democrats have encouraged all members of Congress, party leaders and delegates not to attend the event. Mr. Trump, in contrast, wanted to forge ahead with a raucous, flag-waving celebration that would show great enthusiasm for his struggling campaign and prove that the country was roaring back from the worst of the pandemic.

In the end, though, the dissolution of Mr. Trump’s convention was the latest example of the president bowing to the realities of a health crisis that shows no signs of abating, and the limits of his abilities to bend events to his will.

Some Republicans described a private sense of relief that Mr. Trump had not decided to forge ahead. Yet there was also frustration on Friday that the convention saga had dragged on so long, costing the party valuable time and money that was used in a fruitless attempt to satisfy Mr. Trump’s desire.

The lack of a convention represented a “missed opportunity” for the G.O.P. to boost itself in a key swing state, said Art Pope, an influential Republican donor in North Carolina. Mr. Pope lamented that the gathering had been uprooted from his own state, but acknowledged the pandemic might have made cancellation inevitable.

“I had already decided I wasn’t going either to the Charlotte convention or the Florida convention,” he added.

Mr. Trump hasn’t abandoned his Florida plans altogether, however. He has fund-raisers scheduled for July 31 in Tampa and Aug. 1 in South Florida. Donors who contribute $50,000 were promised photos with the president, and those who give $100,000 were told they would be able to participate in a round table with him.

Before Mr. Trump’s convention announcement, Mr. Curry, the Jacksonville mayor, had asked Tommy Hazouri, the City Council president, to postpone a meeting on Friday to discuss an emergency ordinance regarding convention funding and logistics.

“They weren’t ready,” said Mr. Hazouri, a Democrat. “They didn’t have the answers, and they didn’t want to be embarrassed.”

Mr. Hazouri assumed that Mr. Curry wanted to buy time over the weekend “to try to get answers, but also find out where everything stood nationally.”

“I think, quite frankly, that something was in the hopper, because I don’t know that the president woke up one day and said, ‘I have to worry about the virus,’” Mr. Hazouri said. “Nevertheless, I’m thankful for what he did.”

Maggie Haberman and Kenneth P. Vogel contributed reporting.