It began last month with one forged signature.

Terry Bradley, the wife of an Upper Darby Democratic campaign strategist, said she didn't sign former U.S. Attorney Pat Meehan's nominating petition to run as the Republican candidate in Delaware County's 7th Congressional District.

And she's not the only one.

A deeper look at Meehan's petitions reveals what appears to be a pattern of potentially fraudulent activity that could result in criminal charges.

Last month, after Meehan's neighbors in Drexel Hill told him someone had forged their names on his petitions, he gave county District Attorney G. Michael Green a stack of questionable petitions purportedly circulated by Upper Darby GOP activist Paul Summers.

State Rep. Bryan Lentz, the likely Democratic nominee in the congressional race, is trying to get Meehan kicked off the ballot, claiming that thousands of Meehan's signatures are defective.

Even if Meehan survives the court challenge, the criminal investigation into his petitions could dog him for months and hinder the National Republican Congressional Committee's efforts to take back the seat being vacated by Democrat Joe Sestak.

Green, who contributed $1,000 to Meehan's campaign last year, referred the case this week to state Attorney General Tom Corbett. His investigators won't have to dig too deep before red flags start popping up:

* Rita Lamb's name appears on Meehan's petition - three times. But she told the Daily News she didn't sign any of them. "No I did not sign them, absolutely not," she said.

* Domenic Pino said that he signed Meehan's petition this month and that it had been circulated by Steve Valerio, a Ridley Park official. But John McNichol, the longtime chairman of the Upper Darby GOP, is listed as the circulator on that petition.

McNichol conceded yesterday that he hadn't been the circulator, yet he signed a sworn affidavit claiming that he had been.

"That petition was dropped off," McNichol said. "To the best of my knowledge, [Valerio] said, 'I forgot to sign the petition.' "

* Robert Cornett of Drexel Hill said he signed a Meehan petition that Summers claims to have circulated. But Cornett said he was told it was a petition to reduce local property taxes. And the circulator, Cornett says, was a man in his early 20s - not Summers, who is 58.

"That was not the guy that was at the door, I can guarantee you that," Cornett said of Summers.

* Kathleen Pride, who lives three blocks from Meehan and sees him at church every Sunday, said she would have signed the petition, except no one brought it to her door. Yet, someone signed her name.

"The whole thing is really weird," she said. "I can't imagine Pat Meehan having anything to do with that."

Summers, a strong ally of McNichol's, claims to have gathered 643 signatures on March 6 and 7, which, by the Lentz campaign's calculations, means he averaged one signature every 4 1/2 minutes for 48 hours straight.

In addition to the apparent Meehan forgeries, the Daily News has identified voters who say their names were forged on petitions Summers claims to have circulated for Republican state House candidate Maureen Carey.

Additionally, Summers' own name is spelled three ways on Meehan's petitions, raising the question of whether other party officials were involved. Summers has not returned phone calls from the Daily News seeking comment.

Lentz's campaign says it has evidence that other Republican circulators also forged signatures. He has scheduled a news conference today at the federal courthouse in Philadelphia, calling for the U.S. Justice Department to investigate.

"The Meehan campaign and the Republican machine in Delaware County are one in the same, and the petition drive that they ran was done with a general disdain for the law," Lentz said.

Responding last night to the evidence of potential fraud that continues to emerge, Meehan spokesman Pete Peterson said: "Pat believes that any circulator who engaged in criminal activity should be held accountable, but the Lentz campaign's accusation that Pat was involved in overseeing the signatures is just completely false."

Peterson said petition circulators, not the candidate, are ultimately "responsible for the signatures on their petitions."

This week, Magisterial District Judge David Murphy, an Aston Township Republican, was charged with hundreds of felony counts for allegedly forging names on his own nominating petitions last year.