Stephen Sweeney is one busy guy.

As president of the New Jersey Senate, the Gloucester County Democrat travels throughout the Garden State, shepherds party lawmakers into line, and alternately battles and compromises with Gov. Christie.

He has stepped in as acting governor twice in the last year, most recently while Christie and Lt. Gov. Kim Guadagno have been out of state following last weekend's snowstorm.

He holds a full-time job as an organizer for Ironworkers Union Local 399 and also serves as director of the Gloucester County Board of Chosen Freeholders.

After this week, the state's third-most-powerful elected official will have one fewer thing to do.

Sweeney, 51, announced Wednesday that he would resign from the freeholder board, effective Friday.

"My schedule is obviously intense," explained the West Deptford resident, who said several months ago that he would announce his departure from the board before the year's end. "The responsibility of being president of the Senate, which takes me all over the state, was just an enormous amount of work for me."

Had he not stepped down, Sweeney said, he would have been on the ballots for the Senate Third District and freeholder board elections simultaneously in 2011.

"I never dreamed that I would leave [the board], but I never dreamed that I would become Senate president either," he said.

Sweeney has been a freeholder for 14 years, 13 of them as director. Robert Damminger, the current deputy director, will assume Sweeney's position, and county Democrats will select a replacement to fill the board's vacant seat until a new freeholder is elected in November.

Sweeney, who was sworn in as Senate president in January, said he had been diagnosed with diabetes.

"My schedule being . . . as packed as it is wasn't helping my health condition," he said, noting that he sometimes goes all day without eating.

Sweeney said he was proud of regionalizing more services in Gloucester County, including tax assessment and emergency management.

"We got people thinking outside the box, and it's not just sharing services with towns. The county itself is finding ways to do things more cost-effectively," he said.

Sweeney has taken heat for holding more than one public office. Legislation passed three years ago banned dual-office holding, but exempted those already elected. Christie has pressed for a law that would ban the practice entirely.

Despite the criticism, Sweeney he said he would not urge the Legislature's nine other dual-office holders to step down from their other public positions.

"I believe in the voters' right to choose who they want to serve them," Sweeney said.

Contact staff writer Maya Rao at 856-779-3220 or mrao@phillynews.com.