The United States does not have a left-wing party and a right-wing party. We have a center-right party and a far-right party. The Democrats used to be more left-wing, but that was before Reagan, the Christian Coalition, and the DLC.
A view of U.S. politics from a Swedish perspective:
US politics don't have a Left. Looking at the presidential candidates, I am frankly appalled. None of them would be a viable politician in Sweden. They all support the death penalty, none advocates strict gun control and all make frequent mention of their religious beliefs in public. These are extremist stances. Not even the tiny Christian Democrat party mentions God publicly in Sweden, for fear of alienating the pragmatic rationalist majority.
Imagine how much better the world might be if our parties feared "alienating the pragmatic rationalist majority."