Three weeks out from the first-in-the-nation Iowa caucuses, 52 sitting members of Congress have endorsed GOP presidential hopeful Mitt Romney. And Romney, through his leadership PACs, has donated to 48 of them, according to research by the Center for Responsive Politics.
http://www.opensecrets.org/news/2011/12/how-much-love-will-contributions-buy.html
I’ve seen this; but I can’t imagine that this is a practice in which only Mitt Romney practices.