Competitive primaries and party division in congressional elections

• We distinguish between competitiveness and divisiveness and examine their effects on general election turnout and outcomes.
• Competitive Republican and competitive Democratic primaries increased turnout in the 2010 congressional general elections.
• Divisiveness, measured as the presence of the Tea Party, increased the Republican Party's vote share in November.
• The presence of both competitiveness and divisiveness is no more beneficial to the Republican Party's electoral advantage.

We examine the effects of competitiveness and divisiveness in the 2010 congressional election, as the emergence of the Tea Party resulted in many competitive Republican primaries and highlighted significant divisions within the party. We find that competitive Republican primaries and competitive Democratic primaries increased turnout in the general election. The presence of divisiveness in the Republican Party has no discernible effect on turnout on its own, but actually increases the vote share captured by the Republican Party in November. Additionally, we find that while either a competitive primary or the presence of a Tea Party candidate was advantageous to the Republican Party, the presence of both in the same election was no more beneficial than if there was either a competitive primary or a division in the party.