Sources suggest that California progressive Rep. Ro Khanna’s legislation that would give states flexibility to design a single-payer health system using money from all existing public programs would be a heavy political lift, particularly since seniors are wary of changes to Medicare and employers oppose policies that give states authority over self-insured large group plans. Khanna introduced the bill, titled the State-Based Universal Health Care Act, on Nov. 8 to create a waiver states could apply for that would allow...