Public health experts and scientists closest to the process of developing and testing vaccines for COVID-19 said they're confident the process is based in solid science, despite the perception that the Trump administration's "Operation Warp Speed" would rush the process to have a vaccine available before the election.

President Donald Trump has repeatedly contradicted public health officials in his administration on when a vaccine could be approved and available, often emphasizing how quickly it could be done. The White House announced Operation Warp Speed to help accelerate that process by working with manufacturers to produce doses of vaccines and materials needed to distribute them before the vaccines themselves are approved.

"At first I thought it was a good term," said Dr. Walter Orenstein, professor and associate director of the Emory Vaccine Center. Now, Orenstein said, "I think it has given people a perception that corners will be cut. To my knowledge, none of those corners are being cut."

But officials like Dr. Anthony Fauci, director of the National Institute for Allergies and Infectious Diseases, said that just because the vaccine process is moving quickly doesn't mean they're cutting corners.

"The pace of it relates so much more to the technological advances of the platform technologies that are being used right now," he said during an event with Harvard University this week. "We truncated a lot of time. It has nothing to do with safety, we haven't even gone near a person yet. It was only the technological advances. Right now the FDA is not cutting corners, but they're doing things in a much more rapid, expedited way."

Scientists who are working on the various coronavirus vaccine candidates agreed, noting that the rapid pace of development is the result of a financial investment, rather than a scientific shortcut.

Developing a new vaccine is expensive. Traditionally, cost-conscious pharmaceutical companies move slowly, starting with a product in a so-called "Phase 1" of testing and ensuring it works before moving on to larger (and more expensive) Phase 2 and 3 trials.

Now, all those steps are happening simultaneously -- at great financial cost but not in a way that sacrifices the scientific integrity of the process.

"I think going very quickly doesn't necessarily translate into being rushed. Rushed has a conception of being sloppy. Moving quickly can be done by improving efficiency and downtime," said Dr. Dan Barouch, professor of medicine at Harvard Medical School, who is involved in Johnson & Johnson's vaccine effort.

"All these phases of clinical trials go through a huge amount of safety testing. None of those safety tests are being skipped," said Deborah Lynn Fuller, professor of microbiology at the University of Washington School of Medicine.

Meanwhile, companies are scaling up manufacturing before it's clear if the vaccines work -- many with the financial backing of Operation Warp Speed.

"The leading companies are starting to mass-produce vaccines now, even before there's any evidence of success," said Barouch. "If the vaccines fail, they will take millions of doses and discard them. ... That has never been done to the best of my knowledge in pharmaceutical history."

Democrats on committees with oversight of the federal coronavirus response and experts connected to the process have continued to press officials and ask questions about how they will respond to potential political interference.

Paul Offit, director of the Vaccine Education Center and a physician in the Division of Infectious Diseases at the Children's Hospital of Philadelphia, serves on the Food and Drug Administration's vaccine advisory committee that will be reviewing data on COVID-19 vaccines.

Offit said he's concerned the Trump administration could apply pressure to approve a vaccine that Operation Warp Speed has supported because millions of doses already exist, even if the data is still preliminary. He said even the appearance that decisions around vaccines are politically motivated could undermine confidence they are safe.

"What could happen is that the vaccine is far less effective than you think it is, in which case you've shaken what is a fragile vaccine confidence in this country, or that it has a safety problem that would have been picked up in 15,000 or 20,000 people but wasn't picked up in only a few thousand people," he told NPR.

Twenty-seven percent of American adults said they wouldn't get vaccinated against COVID-19 if a vaccine is approved, according to a ABC News/Washington Post poll conducted in May. Half of those people said they don't trust vaccines in general.

Trump was asked this week if we could see a vaccine by Election Day this year and he said he's optimistic that could happen. When asked if it would benefit him in the election, Trump said, "it wouldn't hurt" but that isn't why he's pressing the agencies to move quickly.

"I'm doing it not for the election. I want it fast because I want to save a lot of lives," he told reporters at the White House on Thursday.

Public health experts in the administration, like FDA Commissioner Stephen Hahn have repeatedly emphasized they won't cut any corners on a COVID-19 vaccine and that the FDA is following all its usual procedures to ensure a vaccine is safe and effective before it's made available. The FDA is an independent agency within the government and Hahn has said vaccines supported by Operation Warp Speed aren't receiving any special treatment.

"I have been asked repeatedly whether there has been any inappropriate pressure on the FDA to make decisions that are not based on good data and good science. I have repeatedly said that all FDA decisions have been, and will continue to be, based solely on good science and data. The public can count on that commitment," he wrote in a Washington Post op-ed on Wednesday.

A vaccine will only be authorized by the FDA once it has generated enough evidence it works in massive, late-stage trials that include 30,000 people. And Hahn has said the agency will consult with an advisory board of experts who are vetted for potential conflicts of interest.

If a vaccine is deemed safe and effective by the FDA based on the evidence generated from those trials, it will likely be given to frontline workers and other people who are particularly vulnerable to the virus before it's made widely available.

Even if a vaccine reports data from clinical trials and is approved by the FDA by later this year, Fauci recently testified it would be available to most Americans "over a period of time in 2021," based on how it is phased in and distributed.

Scientists working on the process to develop a vaccine also said they haven't seen any political influence on the process, and would be some of the first to raise the alarm if they did.

"The public perception is critically important," said Barouch, because if the public doesn't trust a vaccine, they are less likely to volunteer in large numbers for late-stage studies, and less likely to take a vaccine once it becomes available to the general public.

"That can make it tougher to recruit (for studies) because then people don't trust," said Dr. Arthur Caplan, director of the Division of Medical Ethics. New York University Grossman School of Medicine.

Like most scientists, Caplan is a big supporter of vaccines generally. He was one of the last children to develop polio in the United States before scientists successfully eradicated the disease with a mass vaccination campaign.

"I am nervous that if this thing isn't framed right, that we scare people by talking about speed," Caplan said.

This report was featured in the Friday, Aug. 7, 2020, episode of “Start Here,” ABC News’ daily news podcast.

"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.