Wichita ? Unions in four Midwestern states are facing an unusually high number of decertification efforts from dissatisfied workers or their employers, the National Labor Relations Board said Friday.

In the region served by the Kansas City office of the NLRB — covering Oklahoma, Kansas, most of Nebraska and half of Missouri — the NLRB now has six pending decertification petitions and three others scheduled for election, said Michael McConnell, assistant to the regional director of the NLRB.

That does not include Thursday’s decertification election at Boeing Co.’s Wichita facility — where professional and technical workers decided by a slim 64-vote margin, out of more than 3,000 cast, to keep representation by the Society of Professional Engineering Employees in Aerospace.

“This is an unusually high number of these things to be pending at one time. It is a blip. … It is not our experience to have this many petitions pending at one time,” McConnell said.

McConnell said he could not explain what was driving the present surge of decertification efforts.

“I haven’t had any indication of that. Sometimes it ebbs and flows with political winds,” he said. “We have noticed in the past with Republican administrations there are more decertification petitions.”

It also is uncertain how much the nation’s economic condition is driving the trend, he said. Sometimes dissatisfaction created by a poor economy is taken out on the union, but sometimes it has the opposite effect and people come to the union because of layoffs or loss of benefits, he said.

Before the NLRB will even consider holding a decertification election, at least 30 percent of the represented workers must sign a petition seeking a vote.

Historically, petitions for decertification are far rarer than those seeking to bring in a new union. Since the 1940s, the Kansas City office of NLRB has handled about 1,700 decertification petitions — compared to 12,000 petitions seeking union representation, McConnell said.

McConnell said he did not know how many of those decertification efforts succeeded.

Embattled union representatives, who successfully fought to keep their representation at Boeing’s Wichita plant, said they had been so wrapped up in their own efforts they haven’t paid much attention to what was happening elsewhere.

But Jim Singletary, a union contract administrator in Seattle who came down for the Wichita vote, said part of the pressure on unions was coming from things like the Bush administration’s plans to change overtime pay rules.

“Theoretically, if we can’t negotiate overtime for employees, we could lose it,” Singletary said. “That is a scary thought to our employees.”

The decertification effort at the local in Wichita was the first to come to a vote for the aerospace union, he said. The union was voted in at the plant in 2000 by a similarly close margin.

“We haven’t done an outstanding job of trying to communicate with everybody, but it is hard to do when you have 3,500 people and it is a new unit,” Singletary said. “They have never been unionized before.”