Republicans have had an eye on the congressional seat held by Democrat Matt Cartwright in northeast Pennsylvania since the moment he beat Rep. Tim Holden in a Democratic primary 10 years ago. Holden, a Blue Dog centrist, 10-term incumbent, and dean of the Pennsylvania congressional delegation fell to Cartwright in the Democratic primary in 2012 by a whopping 14 percentage points.

Holden’s constituents had moved farther left, making him more vulnerable in a primary.