On Sunday the nation’s top infectious disease expert, Dr. Anthony Fauci,  expressed some cautious optimism that some parts of the country could begin relaxing shelter-at-place orders during the coronavirus pandemic as early as next month.

“I think it could probably start at least in some ways maybe next month,” Fauci said during his appearance on CNN’s “State of the Union” on Sunday. “We are hoping by the end of the month we can look around and say, ‘OK, is there any element here that we can safely and cautiously start pulling back on.’ If so, do it. If not, then just continue to hunker down.”

President Trump on Friday offered what might have been his most optimistic take to date on U.S. efforts to counter the spread of the coronavirus and suggested the country could begin to reopen by May 1.

“People want to get back to work. … We are setting up a council of some of the most distinguished leaders in virtually every field, including politics, business and medical. And we’ll be making that decision fairly soon,” Trump said on Saturday in an interview on Fox News.

Fauci called for a “rolling re-entry” and a solution “that is not one size fits all” on Sunday, to prevent a potential rebound in Coronavirus cases from a premature reopening.

“It is not going to be a light switch that we say, ‘OK, it is now June, July, or whatever, click, the light switch goes back on,’” Fauci told CNN’s Jake Tapper. “It’s going to be depending where you are in the country, the nature of the outbreak that you already experienced, and the threat of an outbreak that you may not have experienced.”

“If you just say, ‘OK, it’s whatever, May 1, click,’ turn the switch on, obviously, if you do it in an all-or-none way, there’s an extraordinary risk of there being a rebound,” Fauci said.

Fauci has been the director of the National Institute of Allergy and Infectious Diseases since 1984.