Play video content Exclusive 2/27/20 TMZSports.com

Barstool Sports founder Dave Portnoy says he's not worried ONE BIT about reports Tom Brady is looking to bail on NE ... saying, "There's a ZERO percent chance he's leaving!"

Of course, El Pres is a DIEHARD Patriots fan -- everybody knows that -- but he also knows Tom and a bunch of other important people in the Patriots organization. Dude's plugged in.

So, when we saw Portnoy on the streets of NYC we had to ask if he had any inside info on the Brady drama.

"Listen! Tom Brady is not going anywhere," Portnoy says ... "Anybody who says he's going anywhere is an idiot!!"

He added, "The Patriots offer [Brady] the best chance to win the Super Bowl. They're offering him the most money or close to it. He just wants to feel wanted which I don't blame him!"

"Mark my words, there's a ZERO-POINT-ZERO-POINT-ZERO percent chance he's leaving New England. Zero! it may be less than zero!"