Populist parties increasingly emphasize welfare chauvinism. They criticize mainstream parties for cutting and slashing welfare at the expense of the 'native' population and to the benefit of the 'undeserving' immigrant. Given recent electoral success of these populist parties we investigate whether and when mainstream parties ignore or adapt - attack or accommodate - welfare chauvinism.
We evaluate various theories of party behavior and issue evolution, which suggest that mainstream parties adapt if they are losing influence, that the timing of adaptation varies and that ideology matters in how parties adapt. Our analyses of party manifestos, speeches and policies of European mainstream and populist parties (1980-2012) suggest that mainstream parties adapt to populist parties on welfare chauvinism, but there is large variation in who adapts and when one adapts. In our examinations of the Dutch and Danish cases we further highlight important cross-country and cross-party differences.