There now seems little doubt that Republican primary voters have shifted to the right. The question is whether that reflects a move by the country more broadly in that direction"or a shift by GOP candidates outside the mainstream, which could benefit Democrats in November.

Tuesdays primaries gave the latest evidence of the shift among Republican partisans, as the more conservative button was punched repeatedly. Sharron Angle, a staunch conservative fueled by a big tea party push, won a primary in Nevada and will be the Republican...