HARRISBURG, Pa. (AP) -- The first prosecution witness in the public corruption trial of a former state lawmaker spent much of his day Thursday being aggressively questioned about the accuracy of his claims -- and his desire to prevent prosecutors from revoking his plea deal.

Mike Manzo, once a top-ranking staffer in the state House of Representatives' Democratic caucus, testified that he could not recall times, locations and other details about a set of alleged conversations with defendants he disclosed to prosecutors about a month ago.

He was questioned about a Jan. 8 letter from prosecutors to defense lawyers informing them that during pretrial meetings Manzo told them, among other things, that he remembered hearing statements from defendants about the use of bonuses to motivate legislative staffers to campaign.

Those claims could be damaging to former Rep. Mike Veon, currently on trial with three former aides, because they link him more specifically to approving the bonuses than the e-mail evidence jurors have already been shown.

The letter also said Manzo was expected to testify about defendants' statements regarding setting dollar figures to reward those who campaigned, their statements about the use of taxpayer-paid blast e-mails and campaign Web sites, and their statements about dispatching state workers to help out in particular elections.

But under cross-examination by Veon defense attorney Dan Raynak, Manzo said he could not recall telling prosecutors about some of the seven items attributed to him in the Jan. 8 letter. He also had difficulty coming up with times, locations or witnesses for the defendants' statements that he did remember.

"I think the question that anyone is going to ask is when someone comes up with what they said was essentially almost all their testimony within a month of trial, it would be up to the jury whether or not they're going to find that believable," Raynak told reporters afterward.

Manzo also was questioned about his guilty plea a month ago to 10 charges, a plea made two days before prosecutors sent the letter to defendants about Manzo's additional allegations. His plea deal requires continued and truthful cooperation with prosecutors, but Manzo said his guilty plea was not just motivated by a reduction in his potential jail sentence.

"I wanted to stop having this engulf my entire life," he testified.

Veon, Brett Cott, Steve Keefer and Annamarie Perretta-Rosepink are charged with theft, conflict of interest and conspiracy in what prosecutors say was an illegal -- and successful -- scheme to use government resources and workers to help House Democrats reclaim majority status.

Senior Deputy Attorney General E. Marc Costanzo said afterward that prosecutors are confident Manzo is telling the truth and that his new information is corroborated by physical evidence and the testimony of others.

Costanzo said it wasn't until after Manzo pleaded guilty that prosecutors provided to him e-mails and focused their questions on Veon and the other defendants, as opposed to other aspects of the wide-ranging investigation of the Legislature.

"The questions did not become specific as to individual e-mails until the preparation for trial," Costanzo said, adding that recalling specific dates and times of conversations "is just not something that's humanly possible."