UPDATED: 2/24/14 9:58 pm ET
DETROIT (Reuters) -- UAW President Bob King said on Monday the union's appeal of a failed organizing vote at Volkswagen AG's plant in Chattanooga, Tenn., will focus on the actions of outsiders, not VW -- in a clear reference to remarks by Senator Bob Corker, an outspoken UAW critic.
Corker defended himself, saying he had the right as an elected official to speak out ahead of the vote, in which workers rejected the UAW's bid to represent them.
Late last week, the UAW asked the National Labor Relations Board to investigate the organizing vote, citing what it characterized as "interference by politicians and outside special interest groups."
The UAW spent two years trying to persuade the plant's workers to unionize and lost despite cooperation from VW management. Its failure upended plans to use the Chattanooga plant as a springboard to organizing factories of foreign automakers in the American South.
In an interview with Reuters, King said, "Corporate VW acted with great integrity," in the run-up to last week's election.
"Our issue is really with outside third parties trying to threaten and intimidate both the company and workers," King said. "It was certainly not the company."
VW cooperated with the union on the vote, allowing organizers to use its facilities, for instance, while officially remaining neutral.
But a number of anti-union Republicans, including Corker, a former mayor of Chattanooga who now represents Tennessee in the U.S. Senate, urged the VW workers to reject the union. Corker and some members of the state legislature made statements that the UAW characterized as threats that swayed the results.
Just days before the vote, Corker said he had been "assured" that if workers at the plant rejected the UAW organizing drive, the company would reward them by sending new work to the plant. He has declined to name the source of the assurance.
"I just can't imagine -- even as partisan as this NLRB might be -I can't imagine they would try to keep a United States senator from weighing in about things they know about," Corker told reporters in Washington, D.C., on Monday.
He told Reuters that a VW decision on whether to expand the Chattanooga plant appeared to be on hold while the NLRB investigated.
"I think until the issue is resolved, it will be difficult (for VW) to talk with the state about incentives and do all those kind of things," Corker said.
Challenges to union election results typically focus on allegations of improper conduct by management, and labor experts see the UAW's focus on outsiders as complicating their case.
"It is flimsy," said John James, executive director of the Center for Global Governance, Reporting and Regulation at Pace University in New York. Comments by Corker were protected by both free speech safeguards and Congressional immunity, he noted.
But Lance Compa, who teaches labor law at Cornell University in Ithaca, N.Y., said that politicians had gone beyond free speech in their statements.
"The state legislators crossed that line when they said they would withhold economic development support for a new product line in the Chattanooga plant if the employees vote for the UAW. That was an outright threat which poisoned chances for a fair election," he said by email. Corker's comments were also a threat, he added, arguing the NLRB had a case.
Volkswagen had flatly denied Corker's claim that the union vote was related to factory expansion. But days later, the workers voted against the union by a 712 to 626 margin.
King acknowledged on Monday that for complaints against third parties such as Corker, there is "a little bit, not a lot" of precedent regarding where free speech ends and illegal interference begins.
But he asked: "Are we going to allow outside people to do what neither unions or management can do?"