We provide an instrumental theory of extreme campaign platforms. By adopting an extreme platform, a previously mainstream party with a relatively small probability of winning further reduces its chances. On the other hand, the party builds credibility as the one most capable of delivering an alternative to mainstream policies. The party gambles that if down the road voters become dissatisfied with the status quo and seek something different, the party will be there ready with a credible alternative. In essence, the party sacrifices the most immediate election to invest in greater future success. We call this phenomenon tactical extremism. We show under which conditions we expect tactical extremism to arise and we discuss its welfare implications.