Although research at other levels of elected office has shown that incumbency has a powerful, additive effect on votes (Hogan 2004; Jacobson 2009; Krebs 1998), these effects largely have been ignored in presidential forecasting models (but see Abramowitz 2008). Instead, some scholars speculate about the conditional effects of incumbency; specifically, the decreased applicability of the retrospective model when the president is not on the ticket leaving the somewhat-harder-to-blame-or-reward vice president to represent the administration. The difficult-to-predict 2000 presidential election generated some discussion on this point. Although I and others argued (Campbell 2001; Holbrook 2001; Wlezien 2001) that part of the explanation for the forecasting error in 2000 lies with Al Gore's failure to embrace the Bill Clinton-Al Gore record and reinforce retrospective voting, others indicate that the retrospective cue may generally be weaker when the president is not on the ticket (Campbell 2001; Lewis-Beck and Tien 2001; Nadeau and Lewis-Beck 2001). Indeed, Campbell (2001; 2008) argues in favor of only giving half weight to presidential performance variables when the vice president, rather than president, is representing the incumbent administration. The logic here is simple: absent the president on the ticket, it is more difficult to frame the election as a referendum, leading voters to attach less weight to incumbency-oriented considerations. This is not to say that factors such as presidential approval and economic performance are unimportant when incumbents do not run, only that these factors might matter less.