The Dems have never called themselves leftist. They are quite eager to point out that they are the Neoliberal party: “We’re capitalist, and that’s just the way it is,” - Nancy Pelosi.

Unfortunately, when you've got 2 choices, one being "Let's round up the pinkos" and the other being "Nothing will fundamentally change", the actual Leftists have to choose the lesser of two evils.