Parties aim for partisan advantage, not just civic charity. In a marginal English constituency during the 2014 elections, our randomized field experiment compared Conservative canvassers' leafleting and door-knocks.

Experimental Design: Randomized contact assignment by party supporters in targeted interventions. We analyzed voter turnout responses across partisan lines to reveal how campaigns strategically shape the electorate without broad mobilization goals.

Key Findings: Impersonal campaign leaflets proved as effective as personal visits at boosting Conservative support, even though leafleting failed to increase overall turnout significantly. Labour self-identifiers showed a notably lower response rate when targeted by Conservatives.

Real-World Relevance: This finding suggests that parties can selectively influence voters without universal civic benefits—exactly what political scientists predicted might happen in partisan contexts.