We caught up with the former CNN anchor Friday at LAX where he warned MAGA supporters to keep an eye on just how involved the singer-songwriter opts to be during this presidential campaign.

Lemon says TS wields a ton of power and influence, and while she's not exactly his generation ... he gives her all the props for fighting for her catalog and becoming a self-made billionaire.

As we reported ... members of Trump's inner circle are reportedly ready to go to "holy war" with Taylor if she decides to endorse President Biden -- as she did in 2020 -- but Don thinks it will take more than one-liners to combat her impact on the election.

Translation: underestimating her could sink DT's White House dreams.

This all falls in line with what FOX11 political reporter/anchor Elex Michaelson said on "TMZ Live" earlier this week ... warning Trump's going toe-to-toe with Swift, and Swifties, is a risky strategy.

Although, he does see a scenario where Swift ends up helping both candidates -- basically, Trump could use a Taylor endorsement for Biden to blast Hollywood elitism, and mobilize his supporters to get out and vote.

There has been a vocal minority hating on T-Swift ... even celebs like Plies, who are getting tired of seeing her all over their TVs when they're watching a football game -- so it's not far-fetched to imagine that hate motivating Trump backers.