Rep. Bob Walker (R-Penn.) announced today that he's retiring from Congress after 20 years service. Though virtually unknown outside political circles, Walker has long been a principal ally of House Speaker Newt Gingrich. The first to join Gingrich's Conservative Opportunity Society, he helped the Speaker become Minority Whip during the eighties and frequently used his extensive knowledge of House parliamentary procedure to rattle his Democratic opponents. Walker now leads the Science Committee. He told constituents today he never intended to spend his entire career in Congress and it's "the right time to move on." But TIME's Larry Barrett notes a recent setback may have affected Walker's decision. "Despite the support of Gingrich, Walker lost his bid for Majority Whip to Tom Delay (Tex.) and he's faded somewhat since then. Still, Walker has always been a proponent of term limits and it's possible he's simply staying true to that principle."