While county-level politics tend to be competitive, Northumberland is a Republican county in most statewide elections. The margins of victory in the county for the Republican presidential candidate in 2000, 2004, and 2008 have been 13, 21, and 14 percentage points, respectively. Governor Ed Rendell narrowly carried it against Lynn Swann while Republican Rick Santorum narrowly carried it against Bob Casey in 2006. The only Democratic statewide candidate to carry the county in 2008 was incumbent Auditor General Jack Wagner. In 2011, the election of Stephen Bridy resulted in a three-way split among the county commissioners.