CHARLESTON — Former Gov. Mark Sanford and Elizabeth Colbert Busch are trading barbs over a union donation to her campaign.

The two are vying for the state’s vacant 1st District congressional seat in a special election next month.

Sanford on Wednesday called on Colbert Busch to return a $5,000 donation from the Machinists Union. The union filed a National Labor Relations Board complaint two years ago against Boeing seeking to have the company’s South Carolina jobs moved to Washington state.

Colbert Busch responded she’s a board member of the chamber of commerce and chairwoman of the South Carolina Maritime Association.

She released a statement saying that if anyone believes she’s in the pocket of big labor she has, as she put it, some oceanfront property in Wyoming for them.