Sen. Jim DeMint of South Carolina has placed a hold on the nomination of former FBI agent and police detective Erroll Southers.
DeMint said Wednesday that he is concerned that Southers would let TSA screeners join a labor union.
Senate Majority Leader Harry Reid has accused Republicans of jeopardizing national security by playing politics with Southers' nomination.
The holdup in Southers' confirmation has been highlighted since the airliner attack last week in Detroit.
DeMint appeared on CBS' "The Early Show."