A top official at a Philadelphia-area ironworkers union is facing eight years in prison in what federal prosecutors say was a campaign of violence and intimidation to coerce building contractors into hiring his workers over non-union competition.

Edward Sweeney is a former business agent of Ironworkers Local 401. He received the sentence Thursday after prosecutors say he admitted a role in two arsons, one arson attempt and 10 extortion attempts. One arson target was a Quaker meetinghouse.

The 56-year-old Sweeney pleaded guilty in September to racketeering and arson charges. Prosecutors say he threatened contractors, organized picket lines and arranged arsons, property destruction and other efforts to sabotage construction sites.

Sweeney testified in January against the longtime union head, who was convicted. All told, 12 men were charged. Nine have been sentenced.