(The Center Square) – Firing off one salvo after another, defense attorney Patrick Cotter pressed long and hard on Thursday in his effort to try to make jurors in the sweeping "ComEd 4" corruption case forget almost all of what they heard from the prosecution's star witness this week over a grueling three-day, 15-hours of testimony.

Former ComEd Senior Vice President Fidel Marquez was back on the stand again on Thursday at the Dirksen Federal Courthouse as the role lobbyists play in the ever-changing world of Springfield politics took center stage. At one point, Cotter got Marquez to acknowledge that someone like his client, Michael McClain, working to foster a good relationship with the likes of then-powerful House Speaker Michael Madigan, was simply a case of him remaining true to his craft, which also included directly asking lawmakers to support issues and legislation important to the client they have signed on with.

"It wouldn’t make much sense to hire a lobbyist to not ask a public official for support, right? To just go in and chat and then leave?" Cotter asked, with Marquez nodding in agreement.

A close associate and longtime confidant of Madigan, McClain is now on trial along with former ComEd CEO Anne Pramaggiore, ex-ComEd lobbyist John Hooker and former City Club of Chicago head Jay Doherty in a case where prosecutors alleged they were critical cogs in a pay-for-play scheme to funnel jobs, cash and other perks to known associates of Madigan in exchange for him pushing legislation that aligned with the utility giant's vision for the future.

All four of the defendants have pleaded not guilty, while Madigan and McClain are slated to go trial early next spring in a widening corruption case that includes elements of the ComEd scandal.

As part of a plea arrangement that saw him plead guilty to bribery conspiracy charges, Marquez is now cooperating with the government as their star witness. During their blistering cross-examination, defense attorneys sought to paint him as an opportunist out to save his own skin at any cost, including working with investigators on what to say in the secretly recorded conversations he taped with the defendants that have been played for jurors all this week.

As the day dragged on, defense attorneys turned their attention to ComEd’s nonstop efforts to derail then-Attorney General Lisa Madigan’s 2018 bill to help low-income consumers. Prosecutors have highlighted that ComEd was opposed to the bill because company officials ultimately believed it would mean higher rates for many of its other residential customers.

Throughout the day, the defense made it a point of noting that Madigan was clear in signaling that he would not be angry with ComEd officials if they succeeded in keeping his daughter’s signature bill from making it over the finish line.