Signalling issue salience: Explaining niche party support in second-order elections

Why do many mainstream party voters switch to voting for niche parties in second-order elections? I develop a simple framework to explain niche party switching in second-order elections and propose that some voters defect strategically to niche parties as a way to signal the salience of an otherwise overlooked issue to their preferred mainstream party. Using panel data from the United Kingdom and Germany, I find that vote switching in second-order elections is more common among those who perceive a mismatch between the party they feel close to and the party perceived as best able to handle an issue of importance to them, as well as when they believe less is at stake and when they place much importance on an overlooked issue.