On Wednesday, Vermont Sen. Bernie Sanders, an independent who caucuses with the Democrats, unveiled his latest iteration of "Medicare for All." Unlike the last time he introduced such legislation, in 2013, this bill had 16 co-sponsors — a third of the Democratic caucus. Among those co-sponsors were many potential contenders for the 2020 Democratic presidential nomination, such as Sens. Kirsten Gillibrand (N.Y.), Kamala D. Harris (Calif.), Elizabeth Warren (Mass.) and Cory Booker (N.J.).