In California in 2009, Abel Maldonado, a liberal Republican state senator, made a Faustian bargain with the Democrats who controlled the legislature.
They needed one more vote to pass their budget. He would give it to them in exchange for their okaying his brainchild, a ballot measure to do away with party primaries.
As a result, the legislature sent it to the June 2010 ballot as a referendum that would amend the state constitution and create a one-ballot primary for everything but president, judicial positions, and non-partisan races. Then-Governor Arnold Schwarzenegger, a nominal Republican, announced his support and rewarded Maldonado by appointing him lieutenant governor for a few months (to fill a vacancy).
The voters rewarded Maldonado for his mischief by defeating him for a full term in that year’s election. On the other hand, they passed what had become Proposition 14 by nearly 54 percent. Since then, all candidates, regardless of party, appear on a single ballot in the primary. The top two advance to the general election in November.