That's a fair description of many parts of U.S. politics (although that sounds more applicable to parties rather than individual politicians: note that foreign aid isn't a cleanly partisan issue, e.g. Bush massively increased anti-disease aid in Africa, and many Christian Republicans back such aid very strongly), but as I'll discuss in the relevant post the relevant sort of similarity depends on one's purpose: the variation among politicians (within, not just across parties) does seem to be enough for a narrowly-focused GWWC member (who can dismiss many standard political issues as trivial in terms of her objective function) to identify differences sufficient for politics to beat the direct effects of donations to the current GiveWell/GWWC charities.