A controversial amendment to explicitly deny Transportation Security Administration (TSA) workers collective bargaining rights failed 47-51 in a party line vote in the Senate Tuesday afternoon.

The vote represents a major victory for unions, like the National Treasury Employees Union and the American Federation of Government Employees, that are competing to represent about 50,000 TSA workers.

Sen. Roger Wicker (R-Miss.) proposed the amendment early in the month, just one day after TSA head John Pistole's Feb. 4 announcement that he would give TSA officers, such as airport screeners, some collective bargaining rights, including ones on issues like scheduling.

Wicker argued that Pistole's decision could pose a security risk, since it could impede TSA's ability to move personnel around in emergency situations.

Wicker also said he views Pistole’s move as an effort by the Obama administration to politically reward the unions' loyalty to Democrats. "Frankly, I think many observers would conclude that the current administration is intent on doling out rewards to campaign supporters, and therefore is moving to reverse this decade-old decision and allow for collective bargaining among TSA employees," Wicker said on the Senate floor earlier in the month.

"I don't believe our country needs 50,000 TSA screeners to be part of a union, but the Obama administration does," said Wicker.

But senators who opposed the amendment, like Sen. Joe Lieberman (I-Conn.), countered that unionization would raise morale among workers and translate to "higher job performance and, therefore, better security for our nation."

The Federal Labor Relations Authority last November decided that TSA employees can vote on union representation, and balloting on this question is expected to be held March 9 to April 19.