For the reason that begin of the pandemic, labor unions have loved one thing of a renaissance. They’ve made inroads into beforehand nonunion corporations like Starbucks and Amazon, and received unusually sturdy contracts for a whole lot of hundreds of employees. Final yr, public approval for unions reached its highest degree because the Lyndon Johnson presidency.

What unions haven’t had throughout that stretch is a real gut-check second on a nationwide scale. Strikes by railroad employees and UPS workers, which had the potential to rattle the U.S. economic system, have been averted on the final minute. The fallout from the persevering with writers’ and actors’ strikes has been closely concentrated in Southern California.

The strike by the United Vehicle Staff, whose members walked off the job at three crops on Friday, is shaping as much as be such a check. A contract with substantial wage will increase and different concessions from the three automakers may announce organized labor as an financial pressure to be reckoned with and speed up a latest wave of organizing.

However there are additionally actual pitfalls. A chronic strike may undermine the three established U.S. automakers — Basic Motors, Ford and Stellantis, which owns Chrysler, Jeep and Ram — and ship the politically essential Midwest into recession. If the union is seen as overreaching, or if it settles for a weak deal after a expensive stoppage, public assist may bitter.

“Proper now, unions are cool,” mentioned Michael Lotito, a lawyer at Littler Mendelson, a agency representing administration.

“However unions have a threat of not being very cool when you have a five-month strike in L.A and an X-month strike in what number of different states,” he added.

If the stakes appear excessive for the U.A.W., that’s partly as a result of the union’s new president, Shawn Fain, has gone out of his solution to elevate them. Throughout frequent video conferences with members earlier than the strike, Mr. Fain has portrayed the negotiations as a broader battle pitting bizarre employees in opposition to company titans.

“I do know that we’re on the suitable facet on this battle,” he mentioned in a latest video look. “It’s a battle of the working class in opposition to the wealthy, the haves versus the have-nots, the billionaire class in opposition to everyone else.”

Mr. Fain’s framing of the contract marketing campaign in school phrases seems to be resonating along with his members, hundreds of whom have watched the web periods.

Shunte Sanders-Beasley, a U.A.W. member in Michigan who began working at a Chrysler plant in Indiana in 1999, mentioned she noticed the combat equally.

“Should you observe historical past, autoworkers are likely to set the tone,” mentioned Ms. Sanders-Beasley, who has served as vice chairman of her native and backed Mr. Fain’s marketing campaign for the union’s presidency final yr. “If we are able to win again among the concessions we took, I’m hoping that it’ll be a trickle-down impact.”

A profitable autoworker strike in 1937, which led G.M. to acknowledge the U.A.W. for the primary time, helped set in movement a wave of union organizing throughout a wide range of industries like metal, oil, textiles and newspapers over the following few years.

Labor activists agreed that the present strike may additionally reverberate throughout different industries, the place employees seem like paying shut consideration to the labor actions of the previous yr. “In organizing conferences, they are saying, ‘If they’ll do it, we are able to do it,’” mentioned Jaz Brisack, an organizer with Staff United who had performed a key position within the Starbucks marketing campaign.

However the flip facet is that the strike may inflict collateral harm that creates frustration and hardship amongst tens of hundreds of nonunion employees and their communities.

“The small and medium-sized producers throughout the nation that make up the automotive sector’s built-in provide chain will really feel the brunt of this work stoppage, whether or not they’re a union store or not,” Jay Timmons, the chief government of the Nationwide Affiliation of Producers, mentioned in a assertion Friday.

Increased wages and positive factors for rank-and-file employees may be good for the economic system. However some argue that Mr. Fain’s and different labor leaders’ aggressive calls for may discourage companies from investing in the USA or render them uncompetitive with international rivals.

“Mr. Fain has to consider this, too — the long-term monetary viability of those three corporations,” mentioned John Drake, vice chairman of transportation, infrastructure and provide chain coverage on the U.S. Chamber of Commerce.

Even those that welcome the union’s aggressive stance say it’s fraught with threat. Gene Bruskin, a longtime union official who helped employees at a Smithfield meat-processing plant in North Carolina obtain, in 2008, one of many largest organizing victories in many years, mentioned he strongly favored the strike and the way Mr. Fain and the union are in search of to rally the working class.

However he mentioned a protracted strike may disillusion employees if the union got here up brief on key calls for.

“If the U.A.W. fails to make any important positive factors, significantly on the two-tier stuff, their future might be significantly harmed,” mentioned Mr. Bruskin, referring to a system wherein newer employees are paid far lower than veteran employees who carry out comparable jobs.

Mr. Bruskin additionally nervous that the union may successfully win the battle and lose the battle if the auto corporations reply by shifting extra manufacturing to Mexico, the place they have already got a big presence.

The tens of billions of {dollars} in federal subsidies for home manufacturing of electrical automobiles that President Biden has helped safe ought to restrict that shift and assist hold manufacturing jobs at residence. Many automakers are already finding new crops in the USA to benefit from the funds.

Nonetheless, Willy Shih, an knowledgeable on manufacturing at Harvard Enterprise College, mentioned the automakers may modify their operations in ways in which undercut the U.A.W. whereas persevering with to provide automobiles domestically. Automation is one choice, he mentioned, as is finding new crops in frivolously unionized Southern states.

The Detroit automakers have created joint ventures with international battery makers exterior the attain of the U.A.W.’s nationwide contracts and have sought to find a few of these crops in states like Tennessee and Kentucky. The union is in search of to convey employees at these crops as much as the identical pay and labor requirements that direct workers of the Huge Three get pleasure from, but it surely has not succeeded to this point.

Given these threats, the union might really feel justified in taking a extra formidable posture towards the automakers. The first verify on shifting work to different states would be the U.A.W.’s capacity to prepare new crops, particularly within the South, the place it has struggled to achieve traction for years. Consultants argued that the union would seemingly enhance its probabilities of attracting members there if it may level to massive concrete positive factors.

“The reply is successful a powerful contact right here and utilizing it to prepare large teams of autoworkers who’re at the moment nonunion,” mentioned Barry Eidlin, a sociologist at McGill College in Montreal who research labor.

And there are different methods wherein being too cautious could also be an even bigger threat to the union than being too aggressive. Organizers level out that employees are sometimes demoralized when union leaders discuss robust after which shortly accept a subpar deal.

Critics of the earlier U.A.W. administration accused it of doing simply that earlier than Mr. Fain took over this yr. “We’d be attempting to make sense of how sure issues handed within the first place,” Shana Shaw, one other longtime U.A.W. member who backed Mr. Fain, mentioned of the concessionary contracts autoworkers have been requested to simply accept over time.

Even Mr. Fain’s behavior of framing the combat in broad class phrases might show to be a strategic benefit. A latest Gallup ballot discovered that 75 % of the general public backed the autoworkers within the showdown, in contrast with 19 % who have been extra sympathetic to the businesses.

The widespread public assist means that the autoworkers could also be working in a distinct context from employees in one other strike that famously contributed to a lack of energy for labor: air visitors controllers’ unsuccessful combat in opposition to the Reagan administration within the early Eighties, after which private-sector employers appeared to develop into extra comfy firing and changing hanging workers.

Dr. Eidlin mentioned that whereas the air visitors controllers did not court docket allies within the labor motion, “the truth that Fain and the U.A.W. are messaging extra broadly, actually attempting to construct that broad coalition, speaks to the opportunity of a distinct consequence.”