After Amazon vanquished a rare U.S. union effort last week in a 21-to-6 vote, keeping the retail giant union-free across the United States, a union spokesperson blamed that result on a corporate campaign to make workers fear for their jobs — and told Salon a much larger union campaign could be ahead at Amazon.

“Everything Amazon did had the underlying tone of fear,” said International Association of Machinists and Aerospace Workers spokesperson John Carr.

Amazon did not respond to a Tuesday request for comment on the result and the allegations. Company spokesperson Mary Osako told CNN that the January 15 “vote against third-party representation” showed workers “prefer a direct connection with Amazon,” which she called “the most effective way to understand and respond to the wants and needs of our employees.”

Carr said that the IAM is still reviewing whether it had sufficient evidence to file charges alleging law-breaking by Amazon in the lead-up to the vote among a handful of mechanics at a Delaware warehouse. Under federal law, it’s generally illegal for companies to explicitly punish or threaten workers for supporting a union, but legal to hold mandatoryanti-union meetings and to make “predictions” about dire consequences that could result from unionization. With the help of the firm Morgan Lewis, contended Carr, the company used such “captive audience” meetings to “put an intense amount of pressure on these workers,” and thus “of course they feared for their jobs.”

“Every single day there was a new sort of rumor mill, or means of mis-portraying, misinformation – that we’ll have to ship this work somewhere else, you name it,” alleged Carr. In particular, he said, the Delaware facility had “plans to make lots and lots of expansion,” and “I think they made it pretty clear that that’s just not going to happen” with a union. “They beat around the bush in doing it,” he added, “and I think they were very careful not to cross the line, but you know they plant that seed, put that thought in those workers’ mind.” In order to discourage workers from opening the door to union organizers who visited them at home, said Carr, “Amazon put out a posting that we were going to come during the holidays, and that they had the right to call the police if we didn’t leave.”

While the number of signatures on the pro-union petition that triggered the vote was nearly as large as the total number that voted last week, said Carr, the only six who voted for the union come election day appear to be the same “core group that started this campaign.” Carr argued that if – as organized labor urged in Obama’s first term – Congress had required companies to recognize unions once a majority of workers sign their names in support, “these folks would have a union right now. But you know, the companies just hold all the cards going into these elections. They’ve got the workers – they’ve got them every day…There’s no better fear tactic than the threat of their job.”