While opposition parties are expected to challenge the government and present alternatives, they often support government legislation. Synthesizing key theoretical explanations, this study examines how opposition parties weigh their goals of winning the next elections, joining or replacing the government and influencing policy. It is hypothesized that opposition parties are more likely to oppose bills when they see chances for boosting their electoral prospects or an early government alternation. Conversely, they support bills when they see chances for future coalition cooperation or policy influence. The analyses of parliamentary votes across four established democracies – Canada, Denmark, the Netherlands and the United Kingdom – over 75 years, show that opposition parties strategically prioritize these goals based on bill-specific factors and the institutional context. Most innovatively, office-seeking opposition parties’ strategic behaviour depends on the patterns of government alternation. These findings offer crucial insights into the complex trade-offs opposition parties navigate in parliament.
