Senate Democrats put business lawyer John Ring, President Trump’s nominee for an open seat on the National Labor Relations Board, on notice Thursday that they would go after him for any potential conflicts of interest while he serves on the board.

Democrats at a Health, Education Labor and Pensions Committee hearing on Ring’s nomination repeatedly pointed to the labor enforcement agency’s recent move to vacate its decision in a December case called Hy-Brand involving corporate legal liability. The decision came after the NLRB’s inspector general’s office determined that board member William Emanuel had a conflict of interest and shouldn’t have voted in the case. An earlier inquiry by the Democrats prompted the inspector general’s probe.