Technical workers at an Amazon.com warehouse in Middletown, Delaware had the chance to elect union representation on Wednesday in the first-ever union election held at an Amazon facility. The workers voted 21-6 against joining the International Association of Machinists and Aerospace Workers

“It’s not a big surprise,” says Kate Bronfenbrenner, director of Labor Education Research at Cornell University.

It’s not that the warehouse wasn’t a good target for union organization. After all, Amazon (AMZN) has been criticized for the exhausting nature of its warehouse work — some employees walk 15 miles a day — and its unsafe conditions, such as facilities that lack air conditioning.

The loss didn’t come as a shock because, by holding an election, the IAMAW rejected what has become a successful model for unions: nationwide, comprehensive campaigns to woo new members and force resistant employers to change their practices.

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Union elections, in which workers vote yes or no to be represented by a third party, have long been the primary method for organized labor to build its membership base. But from the 1970s on, privatization, deregulation, and increased global competition have created a hostile environment for unions. At the same time, employers have developed more sophisticated anti-labor tactics. Court decisions over the past few decades bolstering companies’ free speech and property rights have only intensified those antics, says John Logan, labor and employment professor at San Francisco State University. As a result, it’s become tougher for unions to hold elections, which typically occur when a union can show interest from 30% of workers and the National Labor Relations Board gives the go-ahead. These factors, in part, have caused a sharp drop in elections: 1,395 last year, down from 2,352 a decade prior. Overall union membership in the private and public sectors is at its lowest rate, 11.4% in 97 years, according to the Bureau of Labor Statistics. “Unions need to organize new members or they’ll face extinction,” Logan says.

Under these conditions, unions have turned to large-scale campaigns to gain exposure. By staging public protests and generating community support, the campaigns pressure employers to negotiate with a union or to at least stay neutral as unions vie for worker support. Along the way, unions often try to persuade a majority of workers to voluntarily sign union authorization cards that can be used as a bargaining chip against a stubborn employer.

“It’s thought that the [cards are] a better reflection of employees’ true wishes,” says Logan. That’s because the card-signing is not an on-the-spot act like a union election, and employers’ anti-union rhetoric is not as pervasive as it is in the pressure-cooker atmosphere of a 30-day union election period.

The large-scale, public nature of these campaigns also makes them harder for companies to thwart. For instance, when butchers at a Jacksonville, Texas Wal-Mart voted to join a union in 2000, within two weeks, Wal-Mart (WMT) simply closed its 180 meat counters in favor of selling prepackaged meats. (The company says unionization wasn’t a factor in its decision.) Yet the retail giant has not been able to silence its workers’ ongoing nationwide call for higher wages in the same way.

“To take on a multinational corporation, you have to have multinational strategies,” Bronfenbrenner says.

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The big-picture approach has worked recently for organizations like the Service Employees International Union, which won representation among custodial workers through its decades-long Justice For Janitors campaign and unionized security guards through a nationwide drive. The recent Wal-Mart strikes and fast-food walkouts, while not expressly aimed at unionization, have used the same tactic and generated significant attention.

Amazon spokesperson Mary Osako said the vote at the Amazon warehouse indicated the employees’ preference for a direct connection with Amazon, which she said is “the most effective way” for Amazon to “understand and respond to the wants and needs of our employees.” Another company spokesperson Kelly Cheeseman said that Amazon stresses safety at its fulfillment centers and took steps in 2012 to outfit its facilities with air conditioning.

IAMAW spokesman John Carr, meanwhile, did not respond to requests for comment on the outcome of the Amazon warehouse election, but did say publicly that the Amazon workers “understand a successful organizing campaign often requires several election cycles before representation is achieved.” But perhaps Amazon workers should try a different, bigger approach altogether.