Rep. Burchett chopped it up with a photog in D.C. Wednesday -- where he said he doesn't care for a TS endorsement ... cause she lost him when she left country music, and he hasn't cared for her since. So, Swift's seal of approval means absolutely nada to him.

Tim's TS loathing doesn't end there ... he says her NFL influence may be significant with more people than ever tuning into the sport ... but he personally hasn't watched a game in years despite being the captain of his high school football team back in '87 ... so, in his mind, her influence can't be that big of a deal.

Basically, he tells the cameraman she's all talk cause she previously came out to speak against Tennessee's Republican Senator Marsha Blackburn ... and it didn't move the needle.

Tim adds that a celeb endorsement doesn't mean much in general ... all it does is just become a scenario where both teams think they've won by bringing in top dogs as backup.

So, that recent poll that showed 18% of voters were "more likely" to vote for a candidate endorsed by Tay? Tim's essentially pouring cold water on it ... saying it's total BS.

While Tim's adamant about his stance, former Tennessee Rep. Jim Cooper, who Taylor endorsed for House of Representatives in 2018, tells TMZ he's got it all wrong -- cause TS' endorsement is the best endorsement you can have -- period.

He says anyone who cares about Taylor having a voice in politics is jealous they didn't get her endorsement ... cause, at the end of the day, she's got a massive 29 million followers on her socials and can easily influence swing states that are really close in numbers.

Also, her fans are well and truly devoted ... meaning they're game for anything, he says.

Jim's a massive Taylor fan ... and says she's handled all politics-related matters with complete brilliance and wholesomeness, which is refreshing. He also can't resist touching on her Travis Kelce romance -- saying it plays out like a Hollywood movie.

Back to Tim though ... he goes on to talk about the current political climate ... expressing hopes more young voters will come out and vote because historically, they don't.