President Donald Trump speaks about the coronavirus response during a meeting with New Jersey Governor Phil Murphy in the Oval Office at the White House in Washington, U.S., April 30, 2020.

President Donald Trump said Thursday that U.S. officials and scientists are working as quickly as possible to produce a coronavirus vaccine, and he asserted that he's in charge of its development in "Operation Warp Speed."

"I hope we're going to have a vaccine and we're going to fast-track a vaccine like you've never seen before if we come with a vaccine. I think they probably will," he told reporters during a White House meeting with New Jersey Gov. Phil Murphy.

"I'm not overpromising," he added. "Whatever the maximum is, whatever you can humanly do, we're going to do."

When asked by a reporter who is in charge of the vaccine operation, Trump said, "honestly, I am."

"I'm really in charge of it," he said. "I think probably more than anything I'm in charge."

Hopes to get a vaccine to market are high, but scientists want expectations to be low for how quickly it can happen. Developing, testing and reviewing any potential vaccine is a long, complex and expensive endeavor that could take months or even years. U.S. health officials have repeatedly said it would take at least 12 to 18 months to produce a usable vaccine against the virus.

The National Institutes of Health has been working in partnership with biotech firm Moderna on a potential vaccine and began early-phase human trials in March.

The Trump administration recently launched a project to accelerate the development of a coronavirus vaccine, aiming to produce hundreds of millions of doses by the end of the year.

Trump also said Thursday that results from the National Institute of Allergy and Infectious Disease indicating that Gilead Sciences antiviral drug remdesivir may be effective in fighting the virus was a "big step."

Trump has touted remdesivir as a potential treatment for the virus. A number of studies are testing the drug to see if it's effective in stopping the coronavirus from replicating, but it is not yet a proven treatment.

On Wednesday, White House health advisor Dr. Anthony Fauci said that data about remdesivir showed "quite good news."