WASHINGTON - MAY 4: Democrats from the U.S. House of Representatives, including (L-R) Rep. John Barrow (D-GA), Rep. Rosa DeLauro (D-CT), and Minority Leader Nancy Pelosi (D-CA), visit after news briefing to unveil legislative proposals on health care at the Capitol May 4, 2005 in Washington, DC. The proposals are that are part of the Democrats New Partnership for America's Future and marks the third in a series of legislative initiatives that promote Democratic priorities. (Photo by Chip Somodevilla/Getty Images)
(Chip Somodevilla/Getty Images)
Mark Critz, PA-12
The Pennsylvania Democrat embarrassed Republicans nationally by handily winning a May 2010 special election, but the GOP may get the last laugh. Western Pennsylvania has borne the brunt of the state's population loss, and Republicans could easily combine Critz into a district with Democratic Rep. Jason Altmire by stretching from Critz's home in Johnstown to Altmire's home north of Pittsburgh. Most of Critz's current territory could end up in the heavily conservative districts of GOP Reps. Bill Shuster and Tim Murphy.