Ferocious winds and tidal surges are expected to inundate the heavily populated and low-lying coast, with the cities of Tampa and Sarasota in the storm's path, amid rising fears of widespread chaos and multiple fatalities.

With Milton coming immediately after lethal Hurricane Helene also hit the US southeast, Donald Trump has sought political advantage from the twin storms by falsely saying aid is channelled away from his Republican Party supporters toward migrants.

At the White House on Wednesday, President Joe Biden slammed the Republican election candidate's "onslaught of lies."

"There's been a reckless, irresponsible and relentless promotion of disinformation and outright lies," Biden said in angry remarks.

Biden said the disinformation was "undermining confidence" in rescue and recovery work and it was "harmful to those who need help the most."

In Florida, officials again warned those in danger zones to seek safe shelter.

"You still have time to evacuate if you are in an evacuation zone," Governor Ron DeSantis told a press briefing.

"This hurricane is going to pack a major, major punch and do an awful lot of damage."

But time was running out.

'Nervous'
 

By Wednesday morning, Milton was located 250 miles (400 kilometers) southwest of Tampa, generating maximum sustained winds of 155 mph (250 kph), according to the National Hurricane Center (NHC).

"Winds will begin to increase along the west coast of Florida by this afternoon," the NHC said. "Preparations, including evacuation if told to do so, should be rushed."

"I am nervous. This is something we just went through with the other storm -- ground saturated, still recovering from that," Sarasota resident Randy Prior, who owns a pool business, told AFP.

Prior, 36, says he plans to ride out the storm at home, after recently toughing out Hurricane Helene, which flooded the same western parts of Florida before wreaking havoc across remote areas of North Carolina and further inland.

"I own a business, so once the storm stops, I've got to be here, help clean up, get everything back to normal. But this one's a big one for sure."

Tampa resident Luis Santiago said he would "close up everything" and leave.

Airlines added flights out of Tampa, Orlando, Fort Myers and Sarasota, as highways clogged up with escaping traffic and gas station pumps ran dry.

Not all Floridians and tourists were hurrying to leave.

John Gomez, 75, traveled all the way from Chicago to try to save his Florida home.

"I think it's better to be here in case something happens," Gomez said.

Political clashes
 

At Walt Disney World in Orlando, which was expected to receive a big hit once Milton crosses the peninsula, visitors were getting a few rides in before the theme parks close shortly after midday.

"It's safe and we're here, so might as well," said Lindsay Moore, 42, who flew in from Hawaii over the weekend.

"We thought about canceling but airlines wouldn't let us."

Trump has repeatedly fuelled conspiracy theories and disinformation about supposed failure by Biden and his vice president, the Democratic presidential candidate Kamala Harris.

"Western North Carolina, and the whole state, for that matter, has been totally and incompetently mismanaged by Harris/Biden," Trump said Wednesday on his Truth Social network.

"Hold on, and vote these horrible 'public servants' out of office."

Harris attacked Trump late Tuesday, asking: "Have you no empathy, man, for the suffering of other people?"

Scientists say global warming has a role in intense storms as warmer ocean surfaces release more water vapor, providing additional energy for storms, which exacerbates their winds.

A report by the World Weather Attribution group published Wednesday said Hurricane Helene's torrential rain and powerful winds were made about 10 percent more intense due to climate change.

"The tragedy is that climate scientists have been warning of this for decades," said John Marsham, a professor at the University of Leeds.

Across the southeastern United States, emergency workers are still struggling to provide relief after Helene, which killed at least 235 people.