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.
Fudge, Umbridge and many others in the Ministry refuse to believe that LV has returned, primarily because they know if it is publicly admitted, violent conflict will ensue. The characters preparing for a war with LV and the Death Eaters are all sympathetic to heroic.
Rita Skeeter and the Daily Prophet are a spot-on representation of most news media, both here and abroad. Nothing factual, completely slanted. Rita even admits to Hermione that "The Prophet exists to sell itself, you silly girl." Hardly paints a pretty picture of the liberal media.