After the attempted bombing of a Northwest Airlines flight on Christmas day, a months-old question for the Senate became a pressing concern for the public: Why is the Transportation Security Administration without an appointed director?

While President Obama did make a nomination to the spot -- one Erroll Southers, a counterterrorism expert and former FBI special agent -- Senator Jim DeMint (R-SC) has held up his appointment for months. His blockade of Southers' nomination is apparently due to President Obama's promise that he would push to allow TSA baggage screeners full union rights.

The objection being, if baggage screeners are allowed to negotiate for better pay, benefits and working conditions, it would somehow place national security at risk.

"DeMint's objection creates a procedural hurdle that will probably take at least three days of debate and test votes to overcome," The Washington Post reported.

Senate Majority Leader Harry Reid (D-NV) has vowed to fast-track the nomination once the Senate returns to session in late January.

Supporters of allowing union rights at the TSA "point out that other workers deemed responsible for public safety—like police and firemen—are heavily unionized," U.S. News and World Report noted in 2008. "And many other federal employees, including those who deal with national security like border patrol agents and customs officers, have the right to collectively bargain."

Speaking to CNN on Tuesday, DeMint defended his objection to the nomination, repeatedly insisting "there's a reason" why the TSA is not allowed to unionize, but never really outlining what that reason is.

At one point, he even appeared to blame illegal immigration on labor unions.

"I think the American people should be aware that the priority of the administration is to submit our airport security to collective bargaining with the unions, even though that's been prohibited since the agency was formed," DeMint explained.

The reason it was prohibited, he said, is because the agency has "a constant need to adjust and to be flexible, to use imagination and to change things."

"We cannot ask a third party union boss whether we can move a screener from one station to another," DeMint added.

The American Federation of Government Employees disagrees with the senator.

"This is not an issue of security," a group spokeswoman said, according to CNN. "There is no evidence that labor union rights have any effect on transportation security officers. This is a dedicated workforce who see their jobs as important to the security of the nation."

"They point to union members who acted after 9/11 and the Fort Hood massacre as well," the host said. "These were union members -- firefighters, police officers -- who essentially acted very quickly, and that your argument doesn't hold water here."

"The union boss that you were interviewing used the customs and border enforcement as an example," DeMint said, though customs and border enforcement had not been mentioned during the segment. "We do have 12 million undocumented aliens in our country and that agency has also had to deal with all kinds of charges for changing prices for parking. They're dealing with the collective bargaining of unions all the time and they're not as effective as they should be."

"John Gage, the president of the American Federation of Government Employees, told CNN earlier this month, 'People who insinuate that being a union member has a nation security implication are just totally wrong,'" Pro Publica noted.

This video is from CNN, broadcast Dec. 29, 2009.