The Democratic Party's emerging radical bloc is alarming, but the leftist group's youthful intemperance could backfire and re-energize Republicans' 2020 electoral prospects. Even before all the hanging chads and miraculously divined ballots have been examined in Florida, newly elected leftist Alexandria Ocasio-Cortez is already engaging in activism in the halls of Congress. On Tuesday morning, the future representative from New York joined a protest organized by the Sunrise Movement outside the offices of Democratic leader Nancy Pelosi to demand immediate action on climate change -- as if the dinosaur wing of the Democratic Party weren't sufficiently extremist on environmental issues....