How seriously does the White House take the issue of airport security? Not seriously enough, it seems. How else to explain the fact that, 15 months into office, the administration still hasn’t been able to appoint someone to head the Transportation Security Administration? By any measure, the TSA is the most crucial part of our defenses against terrorism.

Late Friday the president’s second nominee for the post, Major General Robert A. Harding, withdrew himself after disclosures about his firm, Harding Security Associates, and a $6 million contract for work in Iraq. In January the first nominee, Erroll Southers, gave up after his nomination was blocked for doctrinal political reasons by Sen. Jim DeMint, Republican of South Carolina.

As the Christmas bomber episode all too painfully revealed, this agency and the whole Homeland Security bureaucracy is habitually reactive, not proactive.

You could be generous and say that the White House has just been unlucky in its nominees. Or, as I would argue, you could say that this job hasn’t been accorded the priority and care in selection that it calls for.

Consider this: Originally the TSA had a $7.8 billion budget approved for 2010. Then, after the unanticipated visit of the Christmas Day jockstrap bomber, another $1 billion was added, mostly to speed up the arrival of full-body scanning machines at U.S. airports.

Clearly, there is no lack of political will either in Congress or at the White House to give the agency the resources it asks for. But it’s important to remember that the airport screeners are only the most visible part of its role, the part that we frequently encounter and tend to bitch about. But the agency covers everything that moves—including rail, where there are a whole lot of concerns about the security of chemical and other potentially lethal loads.

What the TSA most urgently needs is an appropriately experienced brain at the top, somebody fully baked in the world of multiple and nimble terrorist plots. Right now the agency is being run by Gale Rossides, one of six bureaucrats chosen to build the TSA from scratch in 2002. By all accounts Rossides is an able administrator and manager but she does not have the intelligence and security background to see round corners—and, believe me, seeing round corners is essential. As the Christmas bomber episode all too painfully revealed, this agency and the whole Homeland Security bureaucracy is habitually reactive, not proactive.

Of the two candidates so far nominated, General Harding and Erroll Southers, it was Southers who seemed an ideal fit. He was assistant chief of airport police in Los Angeles. He specialized in counter-terrorism. I was impressed by his grasp of the inherent vulnerabilities of airports, from the screening process to the perimeters and, particularly, his understanding of how our airports are constantly being surveyed for soft spots.

Senator DeMint didn’t give a damn about airport security. What bugged him was that Southers appeared to be sympathetic to the unionization of the TSA work force. (The agency allows screeners to join unions but does not recognize collective bargaining agreements.)

For his part, an exasperated Southers said, when he withdrew, “They took an apolitical person and politicized my career.” He also felt – and I think he was right – that the White House caved too easily to DeMint.

So here we are at the onset of the peak season of airline travel still with a headless TSA. It’s outrageous and the White House needs to fast track the search and appointment, do a better job at finding the right candidate and stand up for its nominee. Or they could simply re-nominate Southers. But then again, he would probably not want to go through the wringer a second time. Who could blame him?

Clive Irving is senior consulting editor at Conde Nast Traveler, specializing in aviation—find his blog, Clive Alive, at CliveAlive.Truth.Travel.