Wolf said he agreed to be Robertson's chairman because he had worked with him on redevelopment efforts and admired his achievements. But after the mayor was charged, Wolf said, he helped persuade him to step aside.
"I was instrumental in getting Mayor Robertson to withdraw," Wolf said. "And I thought that the way I did it was appropriate."
McCord said it was not enough to quietly lobby in that situation. "Sometimes we have to very publicly stand up," he said.
The hour-long discussion is scheduled to be broadcast at 5 p.m. Saturday and 1 p.m. Sunday. A final debate among the four Democrats competing in the May 20 primary to take on Republican Gov. Corbett this fall will be Monday at Drexel University.
On another front, U.S. Rep. Allyson Y. Schwartz pressed Wolf for "leaving out part of the story" in describing his 2006 sale of the family building-products company, the Wolf Organization, and his return in 2009 to rescue it from near-bankruptcy.
She said Wolf took $20 million cash out of the sale while several hundred employees in lumberyards then owned by the company were laid off because of debt the company assumed to buy out Wolf and his two cousins.
"Running a government is not like running a business," Schwartz said, stressing her 23 years as a state senator and member of Congress working on the nuts and bolts of policy.
"I am the one on the stage who can really say I've gotten things done that matter in lives of Pennsylvania families," she said.
Wolf blamed his company's job cuts on the recession, which decimated the housing construction market, and said he saved hundreds of jobs when he returned. "I did go back and save that business, I went back to my company in 2009 when it was flat on its back and hundreds of people were going to lose their jobs," Wolf said.
He has had a bull's-eye on his back for weeks, with polls showing him up by as many as 25 percentage points - a lead built on a multimillion-dollar TV ad onslaught, funded in part with his own money, highlighting the business turnaround story as well as his service in the Peace Corps and as state revenue secretary.
"It is a very compelling story, and it's true," Wolf said, noting he had disclosed his tax returns, records detailing his company's profit-sharing plan, and the terms of a bank loan that helped finance his campaign.
Former state environmental secretary Katie McGinty once again stayed above the fray.
"There has been lots of fighting in this campaign," she said. "I want you to know that as governor, I'm waking up every day to fight for you. I came from a working family, ninth of 10 kids, from Northeast Philadelphia - my dad a Philadelphia policeman."
The candidates broadly agreed on policy issues, favoring same-sex marriage, a restoration of cuts in the state share of school funding, and taxing the natural gas drilling industry.