The CEOs of American Airlines, Pepsi, Procter & Gamble and many other major U.S. companies warned that shape-shifting tariff threats make it virtually impossible to plan and are spooking consumers.

American, Southwest Airlines and Alaska Air told investors and analysts that leisure travel had already softened and pulled their full-year outlooks because the economic climate makes it too tough to forecast. Procter & Gamble, the maker of Pampers diapers and Tide detergent, said it was considering raising prices on some items. And auto-industry groups representing General Motors, Volkswagen and Toyota sent a letter to President Trump imploring him to reconsider the 25% tariff on car parts that goes into effect May 3, because it will make buying and repairing cars and trucks more expensive.

"We don't know what is going to happen," Robert Isom, chief executive of American, told investors and analysts on Thursday. So the airline is being cautious. "What does that mean? It means that we don't hire as much. It means that we don't bring on as many planes, potentially. It means a reduction in overall economic activity."

The same frustrating limbo looms over people trying to plan vacations, Isom said, adding that nobody relishes uncertainty when they are talking about spending their hard-earned dollars.

More executives, from Goldman Sachs CEO David Solomon to Virgin Group founder Richard Branson, warned Wall Street and the Trump administration of the damage to the economy that tariffs will cause.

Branson said Trump could do lasting harm with his unpredictable trade policies that took a booming economy and shook it to its core. "It's just such a pity because everything was going so bloody well up to about three months ago," Branson said.

Southwest and other U.S. airlines are warning of consumers’ weakened appetite for domestic travel.

White House spokesman Kush Desai said: "Under President Trump, business leaders are making trillions in historic investment commitments [and] driving the robust private-sector hiring reflected in multiple jobs reports."

CEOs have sought to assure investors they can weather the tariff storm, but many also said they hoped the erratic nature of the Trump administration's tariff strategy would end soon. Planning for the future -- and forecasting profitability -- amid constantly changing guidance hasn't just caused several companies, including British drinks maker Diageo, to drop their outlook. It led United Airlines to issue two forecasts: one for a stable economy and another for a recessionary one.

Trump's 90-day delay on imposing so-called reciprocal tariffs has only amped up the uncertainty, Solomon told CNBC. The mood now is completely different than it was as Trump took office in January and the World Economic Forum in Davos was abuzz with optimism that he would usher in a new age of less regulation.

"The level of uncertainty is too high," Solomon said. "It's not healthy and it's affecting investment, spending and planning, and that will have an effect on growth and the economy."

Consumers, meanwhile, are eager to get ahead of the impending hit to their wallets, especially for big-ticket items. Spending at retailers, particularly on electronics and autos, has increased in recent weeks, as consumers try to buy before costs on everything from television sets to trucks go up by hundreds or thousands of dollars, said Richard Fairbank, CEO of Capital One Financial, a credit-card issuer.

That trend has helped fuel spending, for now, even as consumer sentiment sinks. At the same time, the share of people who make only the minimum payment on their credit cards -- a sign they are struggling to keep up with their bills -- is above the prepandemic level.

Companies said Americans could have to pay more soon, for iPhones at AT&T and Verizon to new homes built by Pulte.

Shoppers would have to shell out more for smartphones because there is no way for Verizon to fully absorb all of the tariff costs, CEO Hans Vestberg said. "If the tariff is going to be as high as they say on the handset," he added, "that's just not going to be possible."

Phones and other devices are far down the list of things consumers will part ways with, even as they get more expensive, predicted AT&T chief John Stankey. "Unfortunately, for the customer, we're going to have to come up with some new ways for them to figure out how to digest that increase."

Both companies have raised rates and fees on some wireless and broadband plans in recent years. Verizon this month introduced a three-year price lock guarantee on some service plans to reassure its customer base.

Verizon expects to pass some tariff costs on to shoppers.

PulteGroup, which sold more than 31,000 homes last year at an average price of $500,000, said once tariffs are tacked on to many building materials, that price tag will be $5,000 higher. With duties piled on top of everything from porcelain and tile flooring to water heaters and circuit breakers, every new home will cost 1% more.

"It'll impact every single price point and consumer group that we serve, " said James Zeumer, a Pulte vice president. Procurement teams are minimizing costs any way they know how, he added.

"Keeping it to the 1% that we've talked about is significantly less than what you're hearing from the broader home-building universe," Zeumer said.

Several CEOs expressed frustration that manufacturing and hiring in America doesn't insulate them from Trump's tariff impacts.

RTX Corp, an aerospace and defense company that is spending nearly $350 million to expand its plants in Tucson, Ariz., and Asheville, N.C., said it expects to take a potential $850 million hit this year from tariffs, even after cost-cutting measures, price increases and various duty exemptions.

"Do the rates stay in place as they've been published? How long do they stay in place for? Are we able to further mitigate it in other ways? Do they get rescinded and have other effects?" asked Neil Mitchill, RTX's chief financial officer. "I don't know."

Looming tariffs on building materials are likely to drive up the price of a new home.

A few CEOs voiced support for tariffs. Steel Dynamics CEO Mark Millett said tariffs on imported steel and aluminum were "extremely beneficial." Whirlpool, the Michigan-based appliance maker with 10 U.S. plants, said tariffs will level the playing field.

3M, the Minnesota-based maker of thousands of products, from packing tape to power cables, told investors that preserving its relationship with China was important -- and with 110 factories around the world, it could quickly adjust the flow of its shipments.

"We ship products from the U.S. to China that we could also, instead, ship from Europe into China," said William Brown, 3M's CEO. The company is looking into free-trade zones, pricing strategies and revamping global logistics to meet the moment.

"There's things that we can do to mitigate some of this impact and preserve the relationship and the great business we have in China. Again, it's 10% of our company. It grew double digits last year," Brown said.

Elon Musk, chief executive of Tesla and a significant ally of the president, sounded dispirited when asked about tariffs this week after reporting the worst earnings the electric-vehicle maker has had in years. Musk sighed deeply before addressing the trade war, then said he has advocated for lower tariffs to Trump directly and would continue to do so.

"I just want to emphasize that the tariff decision is entirely up to the president of the United States," Musk said. "Whether he will listen to my advice is up to him."