Colleen M. Kelley led her National Treasury Employees Union in a close, hard-fought election campaign to represent Transportation security officers.

But she lost.

Now her critics say that last week’s defeat will be a significant issue in her reelection effort.

Kelley, who was first elected union president in 1999, faces reelection in August. She’s not worried. Her challenger is enthused.

Though frustrated and disappointed by the loss to the American Federation of Government Employees, Kelley’s opponent, Eddie Walker, said that the defeat has led to an “energized spirit” among his supporters.

“What we have been saying all along is supported” by the TSO election results, he said. “Top-down leadership does not work in government agencies or in a union.”

He used the same argument when he failed to oust Kelley four years ago, and won about 15 percent of the vote by chapter delegates.

“I believe he will get the same results as last time,” Kelley said.

But this time, Walker, president of NTEU Chapter 247 in Austin, Tex., thinks the TSO rebuff will make a difference.

Clearly it was a huge loss on Kelley’s watch.

Both NTEU and AFGE had been organizing officers for years and spent lots of money and resources doing it. The labor organizations lobbied Congress and urged the Bush and Obama administrations to allow the officers, who screen airline passengers and baggage, to vote for a union and to bargain collectively.

Those rights were finally granted in the last several months and the unions slugged it out in two elections. The first ended with no clear winner after a six-week voting period. AFGE won the runoff in a squeaker, giving Kelley’s critics another target.

On his Web site, Walker says Kelley pursued a losing strategy “with all the reckless obsession of a gambler . . . right up to last week’s morale-crushing finale.”

He argues that Kelley focused on organizing officers at large airports, “in the process ignoring the suffering of representation-hungry employees at smaller airports. That approach gave ammunition to our competitors, allowing the myth to arise that NTEU was just in it to win it for the benefit of the organization, not for the employees.”

Although Treasury is in its name and it started with IRS staffers, NTEU represents workers in about 30 agencies, from the Agriculture Department to the Social Security Administration. It is the second-largest federal union, after AFGE.

Walker raises what he calls an “unhappy question: Was a portion of the blame due to the national office’s preference for representing white-collar employees? It’s not — as some critics have said — that TSA was not a good fit for NTEU; it’s that TSA was not a good fit for the current NTEU president.”

To Kelley and her supporters, this is nonsense.

“She gave it [the TSO effort] her best shot and we like the way she handled the campaign,” said Mary Wright, president of the NTEU chapter that covers Colorado. “I don’t hear any heartburn over it.”

Wright thinks the impact of the TSO vote on the union’s presidential race will be minimal. Those who try to make it an issue will be “soundly disregarded,” she said.

Ken Mynatt, president of NTEU Chapter 39 in Tennessee, doesn’t think so.

He is an organizer of the NTEU Contrarians, a group that he said represents about 40 percent of NTEU chapters. Kelley says it’s really only a handful.

Mynatt says that his group has not endorsed either candidate, and he and Walker say they are not working in concert. They do seem to sing from the same hymnal, however. Both talk about giving chapter leaders more power and criticize Kelley for her centralized control.

“In the last few years certain elected officials in the NTEU national office have undertaken efforts to diminish the power of the chapter leaders and create a form of governance resembling a dictatorship,” says the Contrarians Web site.

To the contrary, says Kelley. Chapter leaders were fully involved in the TSO campaign from beginning to end and they voiced support for NTEU’s efforts in conference calls, she said. She doesn’t expect the TSO loss to play any role in the union’s presidential race.

It might not be enough to topple her, but wouldn’t it be odd if such a big defeat had no impact?

“I think that will be considered by a lot of our chapters,” said Michael Royster, president of NTEU Chapter 271, covering Brooklyn and Queens in New York City. “There’s no way you can call it insignificant.”