Mr. Onorato, 48, cited a litany of environmental and development achievements from his two terms as county executive and said they offered a preview of the leadership he would provide for Pennsylvania.

He said the recent economic summit had given an international showcase to those accomplishments.

But the G-20 giveth and the G-20 taketh away.

The North Side native's speech was repeatedly interrupted by demonstrators loudly protesting the actions of police officers confronting crowds in Oakland and elsewhere during the event two weeks ago. As he began to speak in the IBEW hall on the South Side, one activist leapt to the stage brandishing a banner protesting the police actions. At several subsequent points, other demonstrators emerged amid a riser full of union supporters on the candidate's right. Some chanted; some held signs while duct tape covered their mouths.

"What happened at Pitt?'' read one of the banners, which was then wrestled away during the recurring episodes. Police removed the demonstrators from the hall. A smiling Mr. Onorato soldiered on through the interruptions, repeating the announcement speech he had delivered earlier at events in Philadelphia and Harrisburg.