President Biden on Wednesday accused former President Donald J. Trump of “outright lies” regarding the federal government’s response to Hurricane Helene, causing morale issues among emergency medical workers and confusing victims of the storm.

Mr. Biden lashed out at the former president and Republican lawmakers as he participated in a briefing from federal officials about Hurricane Milton, which is expected to slam into Florida’s west coast just two weeks after Helene hit the state.

“The last few weeks, there’s been a reckless, irresponsible and relentless promotion of disinformation and outright lies,” Mr. Biden said. “It’s undermining confidence in the incredible rescue and recovery work that has already been taken and will continue to be taken. It’s harmful to those who need help the most.”

Mr. Trump, who is seeking a second term in the White House, and his running mate, Senator JD Vance of Ohio, have made accusations about the government’s response that have repeatedly been debunked by local, state and federal authorities in the disaster areas.

The former president said at a Michigan rally that Ms. Harris had spent FEMA money on housing migrants. He said no helicopters had been used to rescue people in North Carolina. And he has claimed that FEMA told victims of the storms they would receive only $750.

All of those false claims are part of what Mr. Biden on Wednesday called a “disturbing” pattern of comments.

“Assertions have been made that property is being confiscated. That’s simply not true,” Mr. Biden said. “They’re saying people impacted by these storms will receive $750 in cash and no more. That’s simply not true. They’re saying the money needed for this crisis is being diverted to migrants. What a ridiculous thing to say. It’s not true.”

The president also lashed out at Representative Marjorie Taylor Greene, Republican of Georgia, for writing on social media that “they” can control the weather, without indicating who that might be. She also seemed to suggest that the federal government’s response was designed to not help victims in states controlled by Republicans.

“We’re controlling the weather — it’s beyond ridiculous,” Mr. Biden said. “It’s got to stop, moments like this. There are no red or blue states.”

Alejandro N. Mayorkas, the homeland security secretary, said at the briefing that some of the lies about the hurricane response were hurting efforts to reach people who are affected and who qualify for federal help.

“One of the false narratives is that the federal employees who are actually delivering assistance will take an individual’s land,” Mr. Mayorkas said. “And that is causing individual survivors not to approach the people who are there to help and obtain the relief to which they are entitled and that we have available to them.”

He added that “false information only is fuel for the criminal element to exploit individuals in positions of vulnerability.”