Partisan voters are optimistic about electoral outcomes: their estimates of the probability of electoral success for their party or candidate are substantially higher than the average among the electorate. This has large potential implications for political bargaining. Optimism about future electoral outcomes can make costly bargaining delay look more favorable, which may induce partisans to punish their party for agreeing to a compromise rather than waiting, for example by not turning out to vote. Therefore, party decision makers should take optimism among partisans into account when bargaining. In this paper we use game theoretic modeling to explore the implications of partisan optimism for political bargaining. We show that increased optimism among a partisan group leads to a stronger bargaining position for their party, but may hurt its electoral prospects. Another main finding is that even high levels of partisan optimism do not necessarily cause inefficient bargaining delay