"This is an area of the country where union density is low," said Harley Shaiken, a professor at the University of California at Berkeley who specializes in labor issues.
Still, because of the close margin, Shaiken said he believes the union would have won without statements from Corker and other Republican politicians that played to anti-union sentiment and cast doubt on the plant's future with union representation. Those statements, he said, influenced spouses, relatives and neighbors of, as well as workers at, the plant.
"You've got wives, husbands, family members. They hear these threats and they say, 'What are you doing here? This is a risk,'" Shaiken said.
UAW opponent Sean Moss, who works in the plant's assembly shop as a quality inspector, said he began hearing more from colleagues with concerns about the union in the last days before the vote.
"I'm sure they probably had influence at home, from other members of the family that work, other people that have been through unions who did not have a good experience," he said.
He said the UAW's negative reputation resonated with workers at the plant.
"I think their history was probably the biggest part," he said. "People sat back and looked at what they've done, with regard to the last 30 years."
"The thought was we're doing fine without the unions here, so why start now?" he said.
As for the UAW's next step, leaders said they're still evaluating their next steps. Bob King, the union president, wasn't prepared to say after the vote if the union would try to take legal action because of what he called unprecedented outside interference.
Devin Gore, an assembly line worker who favored the union, said he was too upset to talk about the loss Saturday. He's not giving up on one day being represented by the UAW.
"I'm going to be walking into the plant with a UAW shirt on, come Monday," he said. "I don't think we'll stop trying until we get it."