That puts Jenner in the minority among LGBT Americans, politically. According to a July Gallup poll, 21 percent of lesbian, gay, bisexual, and transgender Americans are Republican or lean Republican, compared with 63 percent who identify or lean Democratic.
There are no hard data on transgender Americans specifically, given they are a very small portion of all LGBT Americans and are much harder to draw a representative sample from. A recent Pew poll showed about 5 percent of this group describe themselves as transgender -- with another study suggesting they represent 0.3 percent of the population at large.
Thus, it should be stressed that the 21 percent figure doesn't apply specifically to transgender Americans.
Note: Bruce Jenner's current name and a male pronoun is used in this post, as he has not requested a new name or pronoun be used.