Ex-Mexico President Vicente Fox, 'I'm With De La Hoya!'

Oscar De La Hoya just got his first MAJOR political endorsement -- with former Mexico president Vicente Fox telling TMZ Sports, "I'm with you all the way!!!"

"Breaking news! Oscar De La Hoya is running for President of the United States. Bravo Oscar! You will make it," Fox told us.

Technically, Oscar isn't running yet -- but he told TMZ earlier this week he was putting together an exploratory team to see if he could get enough support to make a serious run for the White House in 2020.

Enter Fox -- who was President of Mexico from 2000 to 2006 -- who strongly believes Oscar is the right man for the job.

"You are honored and respected all over the world. You are well known in California, supported by all which you've done. You are a fighter. You are a warrior. You do fight for human rights. You do protect and fight for Hispanics and Mexican Americans rights in the United States ... that's you, Oscar."

"I'm with you all the way. You will make it ... President or 'Future President of the United States.' Fight. Win. That country needs people like you."

Not everyone has been as supportive, with Eric Holder and Jim Gray scoffing at the idea of President De La Hoya.

But, Oscar insists he's serious ... and this might be just the support he needs to get things going.

Good luck!