State Senate leader Kevin de Le&oacute;n's opening salvo in the U.S. Senate race against Sen. Dianne Feinstein takes on&nbsp;one of the main frustrations progressives have voiced with her, a refusal to support single-payer health care."I believe that every family, it doesn't make a difference who you are or where you come from, deserves to have quality healthcare. It is a universal right," De Le&oacute;n says in a video released by his campaign Wednesday. "It's not the exclusive privilege of the elite and the wealthy."The concept of single-payer healthcare has grown in popularity among Democrats since the 2016 election, with some members of the so-called Sanders wing of the party urging Democrats to use support for it as a litmus test in 2018.Such a program is unlikely to become law while Republicans control both chambers of&nbsp;Congress.Feinstein has said she doesn't support expanding Medicare to the entire population &ldquo;at this stage" and has cited the cost of doing so as a reason.If he were elected, De Le&oacute;n would join Sen. Kamala Harris (D-Calif.) and 15 other Democratic Senators as co-sponsors of the bill proposed by Sen. Bernie Sanders (I-Vt.).