The United States decides most of its elections by plurality voting, or by systems nearly equivalent to it in practice.
This system has a number of pathologies. If a voter prefers a candidate other than a front-runner, he would do better by not voting for who he prefers. If a party has multiple good candidates for a position, they can only run one or neither will stand a chance.
Fixing this requires a system that allows voters to state more than just a first preference - a fact that has been known for hundreds of years. Many replacement systems have been proposed, but many are faulty or complex.
Range voting not only works well, but is also simple, already familiar to people, and implementable on many current voting machines. The White House should campaign for its adoption nationwide.