Gov. Cuomo gave the green light to a plan by General Motors to test self-driving cars in a large swath of lower Manhattan — while totally blindsiding his rival, Mayor de Blasio, who found out from a press release.

Now City Hall said they may fight the state to block it from happening.

“The city wasn’t given much notice of this idea and we certainly weren’t consulted,” de Blasio spokesman Eric Phillips said today, adding Hizzoner found out about GM’s plan “last night” and that the city “received nothing outside of the press release.”

“We have very real safety concerns,” he continued. “We are obviously looking forward to some detail on this idea before any cars hit the streets.”

GM wants to use lower Manhattan’s tangle of congested streets because it will help test cars’ intelligence in harried conditions, and the company has already begun mapping out a 5-square-mile section of lower Manhattan where its autonomous, Chevy Bolts will roam.

State officials say they repeatedly gave city transit honchos the heads-up starting in August.

“The city was first alerted to this proposal two months ago before GM started preliminary mapping,” said Cuomo spokesman Rich Azzopardi. “They were notified again before the announcement of plans for testing next year was made. Now starts the permitting process with DMV and I’m sure whatever concerns the city may have will be addressed.”

The August notice came in the form of a call between Director of State Operations Jamie Rubin and NYC DOT commissioner Polly Trottenberg, a state official said.

Officials would not delineate the 5 square miles of lower Manhattan where the cars will operate, but the area below 14th Street constitutes less than 6 square miles, suggesting Hizzoner may have to contend with the self-driving cars as he makes his way in and out of City Hall.