Correction: very often it's "elect the (whichever) politician running for President two or three years ago", because people rarely remove the bumper stickers they've applied. Once the next Presidential election starts up they'll slap the new sticker on top of the old one, but in 2006 you were still likely to see "Vote for Bush" or "Vote for Kerry" stickers, despite the fact that Bush was ineligible to run in 2008 (having served two terms) and Kerry was unlikely to run in 2008 (failed candidates rarely get nominated again by their party — not never, obviously, but rarely). By 2008 the Bush stickers had been mostly replaced by McCain stickers and the Kerry ones by Obama stickers, but in 2006 you would still see plenty of bumper stickers from the 2004 elections.