Transcript for After rebuke from Trump, CDC director backed by top disease experts
Good evening and it's great to have you with us here on a Thursday night. We have a lot to get to. That storm, the remnants of Sally now turning deadly. The rescues tonight. And the tornado watch up right now. But we're going to begin tonight with the coronavirus here in the U.S., and the CDC's dire new forecast. That the death told could be 218,000 American lives by October 10th. That's just three weeks from and tonight, the feud between president trump and the scientists. President trump telling American S that the head of the CDC was wrong, that he was confused when he said an initial vaccine could come in November or December, but that it will be well into next year before millions of Americans get it. The president suggesting a different timeline. One that could mean a vaccine is ready before the election. And the president claiming it would be available right away. Leaders in the medical community tonight coming to the CDC chief's defense, hoping to offer the American people a more realistic timeline. But in a polarized country and with politics at play, tonight, what the American people are now saying about whether they even trust this vaccine is coming without political pressure. And so we begin with our chief white house correspondent Jonathan Karl. Reporter: Tonight, the nation's top medical experts are backing up embattled CDC director Robert Redfield, as president trump calls Redfield confused and mistaken about when most Americans will be able to get the covid vaccine. Redfield told congress that even if a vaccine is approved this fall, it will take many more months before it is widely available. I think we're probably looking at third -- late second quarter, third quarter 2021. Reporter: President trump says he called Redfield directly to tell him he is wrong, an extraordinary rebuke of one of the top experts on his coronavirus task force. I think he made a mistake when he said that. I believe he was confused. Reporter: The president has repeatedly suggested the vaccine will be ready before the election and available to the general public right away. We are not looking to say, gee, in six months we are going to start giving it to the general public. No, we want to go immediately. Reporter: But Dr. Anthony Fauci said even if a vaccine is approved this fall, it likely won't be ready for the general population until the middle of next year. The idea of getting the entire population that wants to get vaccinated, vaccinated in a month or two, that's going to be very, very difficult to do. Reporter: The head of operation warp speed, the trump administration's effort to develop a vaccine, recently said essentially the same thing. While some 20 million doses may be ready for vulnerable populations by the end of the year, for the general public, it will take considerably more time. We will ramp up the manufacturing of vaccine doses to be able to, based on our plans, have enough vaccine to immunize the U.S. Population by the middle of 2021. Reporter: Joe Biden says he will trust the scientists, not the president. A president who by his own admission downplayed the threat of the virus, leaving a staggering number of Americans to die. Reporter: Tonight, the CDC projects 218,000 Americans will have died of covid-19 by October 10th. But the president has been trying to convince voters he has done a good job handling it, saying the death count would be much lower if you don't count states controlled by Democrats. If you take the blue states out, we're at a level that I don't think anybody in the world would be at. Reporter: A comment roundly condemned, including by New York's senior senator. What kind of demented person would say that those American lives don't count? Reporter: And Joe Biden tweeted, "The job is to be president of all Americans. For the love of god, start acting like it." And tonight, another former member of the trump administration has turned against the president. Olivia troye, who served on the coronavirus task force as vice president pence's homeland security adviser, tells "The Washington post" that president trump has a "Flat-out disregard for human life." When we were in a task force meeting, the president said, "Maybe this covid thing is a good thing. I don't like shaking hands with people. I don't have to shake hands with these disgusting people." Reporter: Tonight, vice president pence said Troy sounds like a, quote, disgruntled employee. And so let's get right to Jon Karl, with us live from Washington tonight. And Jon, we know president trump is also fighting the CDC director after what Dr. Redfield said about masks, that masks might be more effective even than a vaccine. But there's also news coming in on masks tonight, reports that as far back as in April, the post office was planning to mail out masks to American families nationwide, but that plan was shelved? Reporter: In fact, David, the plan was so far along that the post office actually drafted this press release back in April, announcing it. The press release was just obtained by the oversight group American oversight. And it details 650 million masks to be sent out working with the department of health and human services. The white house did not respond to our questions about why the plan was scrapped, but "The Washington post" is reporting that there were concerns at the white house that the plan, sending out all those masks, would cause Americans to panic. David? All right, Jon Karl leading us off tonight. Jon, thank you.
This transcript has been automatically generated and may not be 100% accurate.