U.S. Rep. Tim Holden, the longest-serving member of Pennsylvania's congressional delegation, has lost his re-election bid in a Democratic primary race in a newly redrawn district.

Personal injury attorney Matt Cartwright spent nearly $400,000 in the race against Holden, who was elected to Congress in 1992 and was one of its conservative, so-called Blue Dog Democrats.

"Tonight is Matt Cartwright's night," Holden said in his concession speech to his supporters Tuesday night. "He has won a hard-fought election, and he deserves our support. He deserves our committment, so I ask all of you tonight, as we move toward the general election, to support Matt Cartwright."

Holden's 17th District was redrawn for this election to include Easton and the surrounding area of Northampton County, as well as Scranton and the surrounding area of northeastern Pennsylvania.

Holden, who had represented Berks and Schuylkill counties since he was first elected 20 years ago, lost a lot of name recognition, with more than 80% of the redrawn district being new territory for him.

"It's been an honor and a privilege to serve in the United States Congress," Holden said. "I think we have accomplished a lot, and I'll never, ever, ever forget what you've done for me." 

Video: Tim Holden's concession speech

Video: Matt Cartwright acceptance speech

Cartwright's campaign hit Holden with allegations that he was too conservative for the district's voters, citing his vote against President Barack Obama's health care overhaul.

Cartwright will face Scranton tea party activist Laureen Cummings in the fall.

Cummings, a nurse and small business owner from Old Forge, was the only Republican on the primary ballot.