Donald Trump's campaign has a new, powerful ally -- football legend Herschel Walker is backing his ex-boss because of two words -- unpolished and trustworthy.
Walker knows The Donald well ... he was a contestant on "Celebrity Apprentice" and toted the rock for the New Jersey Generals -- Trump's USFL team -- back in the '80s.
He tells TMZ Sports he has no issues with Trump's incendiary straight talk because ..."I'm tired of politicians. I'm tired of promises. I know Donald will keep his word. He'll do what he says."
As for Trump's more controversial remarks -- Megyn Kelly and Mexicans -- Herschel thinks he does need to clarify a few things, but adds, "I guarantee his plan is not to deport everyone. If you're good, there will be a path to citizenship."
Walker adds, "He's not a polished politician and I hope he doesn't become one."
For now, he's stopping short of pledging his vote to Trump -- he's got an eye on Ben Carson, too -- but he's buying in to Donald's slogan, "Make America Great Again."
"We're the best country in the world. It's why everyone wants to come here. We have to make sure we stay the best country."