I don’t know if Rowling has specifically said anything about current American politics. I do know that book six begins with a discussion of generic American and British political leaders that is neutral to positive in tone. No specific issues are mentioned other than their difficulties with the press. There is a strong implication that leaders have to do things that they can’t discuss in public.
The movie directors, however, are mostly left leaning. The “W” at the end of the current movie is not a reference to Bush. It is an invention of the director, and I suspect he doesn’t know what it implies in the U.S.
Fred and George put the W in the sky right after the fireworks. Wasn't there a single W as the logo on the skiving snackboxes?? It was for Weasley, I assumed.
Not sure if anyone else mentions this, as I haven’t finished reading posts, but the “W” was for the Weasley’s, who had just set off the fireworks display during the exams, and the books are supposed to be set in the early 90’s, so the references to the poor president at the beginning of book 6 are not about Bush and Blair.
I think they did a good job making the kids invoke the idea of the late 30’s/early 40’s with the cinematography, the posters of Fudge, the newspapers and very often the way they had the kids dressed. (I am a dork, and almost had a degree in costume design, so I always look very critically at costumes!) Yes, they were dressed in “today’s fashions” but the way they would have Neville, for instance, in a zipped cardigan in headshots to make him look more as though he could have been in a movie set during the lead-up to WWII was interesting.
Also, JKR has said many times that she is very interested in the way people handled the growing unease in Europe under Hitler, so it is most definitely (imo) a deliberate reference to WWII and separating people into the camps of “good” and “bad.”