Few people have foreign policy as far to the left as Jimmy Carter
You'd have to define 'leftist' foreign policy. (and his foreign policy was pretty identical to that of, say, Ford, prehaps he was even tougher on the Soviets)
Carter never pushed for health care nationalization as president. Meanwhile LBJ instituted the largest federal health care programs in the nation's history.
Finally you have something, but even this is pretty weak. Marijuana is a very minor issue, and ti say that Carter pushed for it isn't really correct. He affirmed his support for decriminalization in front of congress but never had any intentions of fighting for progress.