America's largest city will become the first to mandate that people show proof of coronavirus vaccines to get into indoor restaurants, gyms and entertainment venues, Mayor Bill de Blasio announced Tuesday.

The mayor said all workers and customers in those industries will have to show proof of at least one dose of the vaccine.

-We're setting the pace!- he enthusiastically said as he rolled out the plan that he is calling "The Key to NYC."

De Blasio pointed to the surging Delta variant as a driving force behind his plan and he included a health scientist at his announcement who talked about the severity of the variant.

-We have a real different threat here- he said, -and we need new measures like this.-

He called his plan a first-in-the-nation approach that will encourage more people to get the vaccines. Hesitancy about the vaccines, even outright hostility, has hampered efforts in some parts of the country where cases and hospitalizations are surging.

The mayor said his plan will take effect Aug. 16, while enforcement will begin Sept. 13.

-We want to give businesses time to get acclimated- he said.

A number of conservative critics have lashed out at the possibility of so-called vaccine passports. A top Republican leader in Oklahoma has been calling vaccine passports a form of segregation, similar to Jews being forced to wear the Star of David during World War II.

A member of the New York City Council who joined de Blasio in the announcement applauded the plan but acknowledged that it would be controversial. De Blasio remained enthusiastic.

-We know this is what is going to turn the tide- he said. -This is an easy approach … just show it and you're in.-