switch hitter
n.— «Recipients of Obama’s summer mailing include many lobbyists who are called “switch hitters” in political parlance—contributors to lawmakers of both parties who seek to open Capitol Hill doors to them on a bipartisan basis.» —“Romney as V.P. could clinch Michigan for McCain” by Robert D. Novak Chicago Sun-Times July 26, 2008. (source: Double-Tongued Dictionary)