By Tony Romeo

LANCASTER, Pa. (CBS) — Challengers turned up the heat on frontrunner Tom Wolf this week, during a pair of debates among the candidates seeking the Democratic nomination for governor of Pennsylvania.

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In a debate seen statewide last night, Rob McCord (fourth from right) continued to hammer Tom Wolf (far right) for his relationship with a former mayor of York who was tried and acquitted on charges of murder in 2002 in connection with a race riot when the mayor was a police officer in that city more than 30 years earlier.

McCord said sometimes elected officials must do difficult things:

“Sometimes you’ve got to be a little tough.  I mean, the person who sticks out for me, and I won’t go into it at length, is the racist behavior of Charlie Robertson.  I think you do the right thing there.”

Allyson Schwartz (second from right) chided Wolf for his support of a former York County state lawmaker convicted on public corruption charges:

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“How do you stand up then, and say, ‘I’m going to make sure there isn’t corruption anywhere in my administration or anywhere in the capitol,’ when you pick and choose when you will excuse that behavior?’ ”

Wolf responded:

“Steve Stetler’s still a friend of mine.  I think he was a good representative, and the Steve Stetler I know is a good human being.  And so I did what I thought was right.”

Later, Wolf quipped that he’s got a bullseye on his back because his rivals have apparently seen the polls showing him with a commanding lead in the race for the Democratic gubernatorial nomination.  Those polls show Wolf with a lead of more than 20 points among Democratic voters.

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