Tom Steyer, the controversial billionaire who ran unsuccessfully for president, is trying to appeal to California voters with a “single-payer” health care policy. He is not alone. Former Congresswoman Katie Porter and former Health and Human Services Secretary Xavier Becerra also proclaim their support for single-payer .  Together, these three are California’s highest-polling Democrats running for governor. And with support for “single-payer,” they are united behind what would be one of the biggest expansions of government power ever proposed in this state. Tom Steyer, the controversial billionaire who ran unsuccessfully for president, is trying to appeal to California voters with a “single-payer” health care policy. Getty Images for CBS Television Stations He is not alone.…