On Tuesday, the Senate voted down a Republican-authored amendment to the FAA Authorization Act that would have eliminated the collective bargaining rights of baggage screeners at the Transportation Security Administration.

These workers, also known as TSOs, were granted limited collective bargaining rights on February 4 in a historic decision by TSA Administrator John Pistole, who was making good on a campaign promise by Barack Obama to allow bargaining rights for the nation’s 40,000 TSOs.

The amendment would have left intact the right of TSOs to belong to a union (12,000 TSOs are already exercising that right as dues-paying union members). However, the amendment would have outlawed collective bargaining, i.e., authorizing the union to negotiate on behalf of TSOs.

The lead sponsor of the amendment was Sen. Roger Wicker (R-Miss.), who argued that giving TSOs the right to bargain collectively could harm national security by limiting the agency’s flexibility. Perhaps he didn’t realize that under the terms of Pistole’s determination, a future TSO union would be barred from negotiating issues that directly affect national security.

Like all federal public sector unions, a TSO union would not be allowed to negotiate salaries. Pistole will not even allow the union to negotiate on basic issues like disciplinary standards.

On the eve of the vote, Sen. Tom Harkin (D-Iowa) took to the floor of the Senate to urge his fellow legislators to defeat the amendment. The senator argued that TSOs should be granted collective bargaining rights as a matter of national security.

He noted that a recent ranking of “Best Places to Work” put the TSA in 220th place, out of 224 federal agencies and departments. Turnover and injury rates at TSA are among the highest in the federal government.

“Low morale and high turnover at a frontline security agency are a recipe for disaster,” Harkin said. “TSA determined that collective bargaining will address those problems and improve the Agency’s ability to fulfill its mission.”

Harkin challenged the assumption that unionization is incompatible with national security, noting that most federal security employees, including Border Patrol personnel, Immigration and Custom Officials, Capitol Police officers and Federal Protective Service Officers have collective bargaining rights.

Wicker argued that TSOs should be treated like the CIA and the FBI, which do not have collective bargaining rights. This despite what seems fairly obvious: The job of a TSO seems to have a lot more in common with that of customs officials in the same airport than with that of an FBI special agent or a CIA operative.

The defeat of the amendment eliminates a major hurdle to TSO collective bargaining. TSOs are scheduled to vote on representation starting on March 9.