Salena Zito

"Even more damning," according to Skelley, "is the fact that 385 of the 942 signatures being contested by Critz were collected by an Altmire staffer who lives outside the district, which isn't allowed under Pennsylvania law."

The requirements are pretty clear, he said, yet Altmire's staff may have made enough mistakes to cost him a place on the primary ballot.

Pitting incumbents against each other is a classic majority-party strategy to wound the opposition. We see such battles every 10 years, following redistricting.

In Ohio, the districts of longtime Democrat U.S. Reps. Dennis Kucinich and Marcy Kaptur were pushed together by the Republican-controlled legislature.

Washington Democrats say they are worried that Altmire may be permanently damaged by not making the ballot or residually damaged going into the general election with a negative narrative about his capabilities.

Washington Republicans are thrilled: They consider Altmire tougher to beat than Critz.

They are classic centrist-conservative Western Pennsylvania Democrats. Obama won just 45 percent of the vote in Altmire's old district and less than 50 percent in Critz's, so each is are capable of winning in fairly purple territory.

The new 12th is about a 45-percent Obama district. So Altmire, having held a Republican-"redder" district in the past and having represented more of the new 12th, indeed might have a better chance than Critz of winning the general election , according to Skelley.

Even without this party spat, or even in a non-presidential year, this district would be front and center in national coverage: It leans right, could easily be held by a conservative Democrat, and is home to voters whom Obama once referred to as bitter and clinging to God, Bibles and guns. 

Salena Zito

Salena Zito is a political analyst, reporter and columnist.