Former Rep. Mark Critz (D-Pa.) will run for lieutenant governor of Pennsylvania rather than seek a rematch for his old House seat, he told a local radio station on Wednesday.

"It's 100 percent — I just haven’t made it official yet," Critz said when asked about a run for lieutenant governor.

The decision deals a major blow to Democrats' hopes of defeating freshman Rep. Keith Rothfus (R-Pa.), who defeated Critz in a hard-fought race in 2012. 

Critz, a centrist known for his strong retail political skills, had been seriously weighing a bid to return to Congress and as recently as June had met with the Democratic Congressional Campaign Committee.

With Critz not running, Rothfus is much less likely to face a tough challenge in his Republican-leaning district.