The ability to put things into perspective. Public life involves all sorts of controversies and complex issues. Having the ability to deal with those details, yet not lose sight of the larger picture, is a key trait of good leadership. The ability to organize and prioritize are of paramount importance to good leadership. The ability to get along with others.
Good leaders are good with people.
Public service is rife with conflict and disagreements, but those who can debate and disagree on policy issues without getting entangled in personality conflicts make good leaders. Leaders should have the ability to control both their emotions and their tongue, remaining cool and calm on the outside even in the stormiest debates. A core knowledge of the issues. If you're going to run for public office, get to know what the issues are. Attend some meetings of the board or position you're running for.