Create an amendment to the United States constitution abolishing the electoral college, in place of a popular-vote election scheme.
In the current system of presidential election, candidates are forced to focus on a small number of "swing" or "battleground" states to secure enough of a majority to take office. This disenfranchises the citizens of the remaining states, as their interests may be overlooked by potential incumbents in their drive for votes.
Several states have already signed the "National Popular Vote Interstate Compact," essentially taking the vote out of the hands of the states electors, and giving the state's electoral votes to the winner of the national popular vote. We can take this a step farther by taking states out of the equation completely.