Prior research has shown that institutions affect parties’ incentives to coordinate within elections or compete on their own. However, no study to date has examined the way that institutions affect when parties coordinate in the most important of electoral contests: the presidential race. In this article, we explain which institutions encourage parties to run as part of pre-electoral coalitions (PECs) or shun them and run on their own in the race for the presidency. Using an original dataset of over 1400 parties that sponsored a candidate on their own or ran as part of an alliance in presidential elections across 23 democracies in Europe and South America from 1975 to 2009, we find that the powers of the presidential office, electoral rules and multi-level governance determine when parties decide to enter the race on their own or form an alliance. Our findings have important implications for understanding party competition in semi-presidential and presidential systems.