Sen. Ben Nelson (D-Neb.) announced Monday that he will oppose the nomination of Craig Becker to serve on the National Labor Relations Board, likely dooming the nominee’s Senate confirmation.

“Mr. Becker’s previous statements strongly indicate that he would take an aggressive personal agenda to the NLRB, and that he would pursue a personal agenda there, rather than that of the Administration,” Nelson said in a statement.

Before Nelson’s announcement Monday, Democrats acknowledged they did not have the 60 votes necessary to move the nomination. The Senate is scheduled to vote on a procedural motion to move to Becker’s nomination Tuesday. That vote was originally scheduled for Monday evening but was pushed back because of inclement weather.

Becker is a veteran of the labor movement who has worked for the AFL-CIO and the Service Employees International Union, most recently as the SEIU’s associate general counsel.

The Health, Education, Labor and Pensions Committee approved Becker’s nomination along party lines last week, with Republicans expressing fear that the appointee would abuse his position to enact provisions in controversial “card check” legislation that allows unions to organize through a petition process. In his statement Tuesday, Nelson voiced similar concerns.

“In addition, the nominee’s statements fly in the face of Nebraska’s Right to Work laws, which have been credited in part with our excellent business climate that has attracted employers and many good jobs to Nebraska,” Nelson said. “Considering these matters, I will oppose the upcoming cloture motion and the nomination.”