Rep. Mark Critz (Pa.) will have his day in court Friday to try to knock Rep. Jason Altmire off the April 24 Democratic primary ballot.

The state court hearing marks the first step in a legal process that could drastically change the outcome of one of the most competitive Member-vs.-Member primaries of the cycle. Polls from both candidates have shown Altmire leading Critz in the primary.

But last week, Critz challenged his opponent’s right to be on the ballot after Altmire filed 1,651 nominating signatures — just a few hundred more than the requisite 1,000 valid names of voters in the district. Typically, campaigns file at least twice the required number of nominating signatures, said Charlie Gerow, a former election attorney and GOP analyst.

“It’s a serious challenge only because Altmire filed so few signatures, and that is both legally and politically problematic,” Gerow said. “My sense is that [Altmire will] probably ultimately prevail on some rather technical grounds.”

The crux of Critz’s case lies with one of Altmire’s junior campaign staffers, Abby Silverman, who collected about 385 signatures for Altmire’s petition. Under Pennsylvania election law, Silverman must live in the Congressional district where she collected signatures.

The Critz team argues that Silverman lives outside the district in downtown Pittsburgh, but she’s registered to vote at her parent’s house in the redrawn 12th district.

If a judge deems Silverman’s signatures invalid, Critz’s team must prove an additional 250 to 300 signatures on Altmire’s petition are illegal. And whatever the judge determines Friday, Pennsylvania insiders say it’s likely the losing side will appeal to the state Supreme Court.

“There’s almost certain to be an appeal from the ruling,” Gerow said.

But the legal process is under a time crunch. Primary ballots will be printed March 12, according to a spokesman for the Pennsylvania Department of State.

It’s unusual for an incumbent to get booted from the ballot for invalid signatures, but in 2010, two Congressional challengers were kicked off their respective ballots in the 1st and 7th districts, the spokesman said.