I happen to be married to a very bright therapist and a behavior hospital administrator and we talk about these issues.
First, there is plenty of research to support the notion that gender identity is not a choice. Second, the authoritative voice on mental disorders is the APA, not the American College of Pediatrics. They develop the DSM-5 manual. They don't classify gender identity as "mental disorder." They set the standards. Literary. Anyone and everyone with a license to practice in the mental health profession defers to APA standards. Doing otherwise means liability and potential for losing said license.
Learn (if you actually want to learn) more about it
here.
Second, as a Republican (assuming you are one) you have zero credibility and absolutely no ground to stand on when it comes to the idea of propagating self serving ideology. GOP invented it and perfected it over the years. Your party still believes homosexuality is a choice that can be "fixed" with some prayers and treatment. Large number of Republicans today are backwards minded, stuck in the past, unable to cope with the progress of modern society scared little gun-loving racist, sexist, misguided nut cakes. The party is made up predominantly of old white man who refuse to yield social and political power to anyone who isn't them. Most of them "Christian," too. Lovely people. That's just the truth - whether you like it or not.