Rep. Mark Critz, edged out fellow a Pennsylvania Democrat, Rep. Jason Altmire, on Tuesday in the latest primary battle that pitted two incumbents against one another.
Altmire and Critz, both conservative Democrats, were drawn into the same district after Pennsylvania lost a seat through the state's redistricting process.
The new district lines initially appeared to favor Altmire, as he has represented two-thirds of the new district's voters. But Critz garnered the endorsements of local unions. It's rare for the lobby to back one Democrat over another. He also scored support from former President Bill Clinton and Rep. Robert Brady, the dean of the Pennsylvania delegation.
The race became a test of the strength of organized labor - which could prove to be a key voting bloc in the November general elections. Critz cast himself as a stronger ally of unions while taking particular aim at Altmire's vote against the 2010 health care reform bill. Democrats were incensed at the time after Altmire initially said that he would back the bill weeks before the final House vote.
Critz entered Congress in May 2010, winning a special election to fill the seat left open by the late Rep. Jack Murtha, the longest-serving House member in Pennsylvania history. Murtha died in office after representing the district for 36 years. Critz served as Murtha's district director for three years after initially joining his staff in 2001.
Also a former congressional aide, Altmire first won election to the House in 2006, upsetting Rep. Melissa Hart, the Republican incumbent. He won re-election by maintaining a centrist record, including the vote against the health care bill. But in this election season, Critz tried to cast Altmire as a disloyal party member.
The primary became heated early in the process when Critz tried to push Altmire off the ballot. He argued that 942 of Altmire's 1,651 signatures were invalid to qualify for the primary.
A Pennsylvania judge ultimately ruled in Altmire's favor that he had properly collected enough signatures. Altmire's campaign subsequently released a statement charging Critz of resorting to "tactics usually reserved for elections to high school prom king, rather than the United States Congress."
Altmire has never missed a vote in his congressional career. And despite the heated primary, the congressman returned to Washington to vote Tuesday night.
Altmire joins Reps. Donald Manzullo, R-Ill., and Dennis Kucinich, D-Ohio, as other lawmakers who have lost their primary to a sitting House member.
He also became the second Blue Dog Democrat to lose Tuesday, as challenger Matt Cartright upended Rep. Tim Holden, D-Pa., as well.
Many thought Tuesday's vote could go either way, especially after a Nor'easter dumped a prodigious amount of snow on the district, diminishing turnout.