Taylor Swift and John Mayer's fledgling romance has already hit the skids - because her protective mother hates his wild past.

The unlikely couple heated up after Taylor's December breakup with Twilight hunk Taylor Lautner. But before the love affair could take flight, her mother Andrea made her disapproval clear, sources say.

"Andrea pulled John aside and told him point blank to back off," an insider told The ENQUIRER. "She said a friendship was fine, but there was no way he'd get close enough to Taylor to break her heart if she had anything to say about it."

Country cutie Taylor, 20, has collaborated with rocker John, 32, on a song for his new album. Despite the objections of Taylor's mom, they enjoyed a Jan. 24 date at the Nashville restaurant Cabana only weeks after a romantic rendezvous at Il Ristorante di Giorgio Baldi in Los Angeles.

But with a string of ex-girlfriends including Jennifer Aniston and Jessica Simpson, along with his reputation as a partier and pot smoker, John is hardly Andrea's idea of a dream date for her little girl. John did not help his cause with Andrea when he recently appeared shirtless on the cover of Rolling Stone magazine and made shockingly candid statements about casual sex.

Despite that, Andrea and Taylor attended the Jan. 26 taping of a CMT Crossroads special in Nashville that featured John and country music superstar Keith Urban.

"Right after John performed, Andrea pulled him aside and basically told him to keep his hands off her daughter," said the source. "She's all for music collaborations, but she couldn't get past his baggage."

And according to the source, John didn't put up a fight.

"All John could do was to offer Andrea a compliment on raising a lovely daughter," said the source. "He said he understood completely, and it was an honor enough to call Taylor his friend."