Like the mayor he serves, Tim Sullivan has deep family connections to unions and quickly in his career established himself as a leader within organized labor.

Sullivan’s father, Gary, a longtime union member, served as president of the Utility Workers Union of America, Local 369. “I grew up knowing what being in a union meant for the prospects of my family,’’ Tim Sullivan said in a college newsletter in 2006. “My dad was able to put three kids through exceptional colleges because he was in a union.’’

Sullivan, acting director of the city’s intergovernmental affairs office, was charged in a federal indictment released Wednesday that alleges he conspired in 2014 to withhold critical city permits from the Boston Calling music festival, until festival organizers agreed to hire unneeded union stagehands.

Sullivan joined Mayor Martin J. Walsh’s administration in February 2014, the month after Walsh took office, as chief of staff in the governmental affairs office. He also serves as Walsh’s senior adviser for external affairs.

Walsh hired him from the Massachusetts AFL-CIO, an umbrella organization representing about 400,000 union workers across Massachusetts. Sullivan had been legislative and communications director for the organization, where he worked for 10 years. He served as a registered State House lobbyist for the organization from 2007 to 2014, according to state lobbying records.

Five years ago, Sullivan briefly mounted a campaign to become president of Mass AFL-CIO, when the union’s top leader, Robert Haynes, announced he would step down. Sullivan ultimately withdrew from the race and endorsed then-state Senator Steven A. Tolman, who won the job.

Tolman said in a statement Wednesday, “While I am not privy to the details of these allegations, I have known Tim Sullivan and his family for years. During the time I worked with him, he was dedicated to two things above all else: his own family and the hardworking men and women of Massachusetts.’’

Walsh is personally close to Sullivan, and told reporters Wednesday morning, “I’ve known Tim a long time. Certainly it goes back many years, back before the State House days.

“You know I’m bothered by this,’’ Walsh said. “Tim and a wife and a young baby at home, a 2- year-old I believe now. So I feel bad for what’s happening here, but certainly it’s something that you know I don’t stand for. If these allegations are true, I’m not happy about them.’’

He defended Sullivan’s ability, saying, “Tim was a very capable agent when he worked at the AFL-CIO and did a very good job in the city working with legislators and working with the City Council.’’

Sullivan graduated from the University of Richmond’s Jepson School of Leadership Studies and in 2012 earned a master’s degree from the University of Massachusetts Amherst, according to biographies posted online.

The city has placed Sullivan on paid administrative leave.

Mark Arsenault can be reached at mark.arsenault@ globe.com. Follow him on Twitter @bostonglobemark.