NEW YORK (Reuters) - Nearly 40,000 Verizon workers walked off the job on Wednesday in one of the largest U.S. strikes in recent years after contract talks hit an impasse, and got a boost as U.S. Democratic presidential hopeful Bernie Sanders joined them at a Brooklyn rally ahead of the New York primary next week.

Front-runner Hillary Clinton, who will face Sanders in the

primary on April 19, also voiced support for the strikers and urged Verizon to go back to the bargaining table.

The strike was called by the Communications Workers of America (CWA) and the International Brotherhood of Electrical Workers that jointly represent employees with such jobs as customer services representatives and network technicians in Verizon Communications Inc's VZ.N traditional wireline phone operations.

The strike could affect service in Verizon’s Fios Internet, telephone and TV services businesses across several U.S. East Coast states, including New York, Massachusetts and Virginia. The walkout does not extend to the wireless operation.

Verizon said it had trained thousands of non-union employees over the past year to ensure no disruption in services.

“There’s no way that these 10,000 people ... can make up for 40,000 people who have decades of experience (in highly technical jobs),” CWA representative Bob Master said.

The wireline unit, which represents Verizon’s legacy business, generated about 29 percent of company revenue in 2015, down about 60 percent since 2000, and less than 7 percent of operating income.

Verizon has been scaling back its Fios TV and Internet service and stopped expanding its landline phone network.

In recent years, Verizon, the No. 1 U.S. wireless company, has shifted focus to the bread-and-butter wireless business and new efforts in mobile video and advertising.

To that end, Verizon bought AOL for $4.4 billion last year betting that a push into mobile video and targeted advertising can help it find new growth avenues.

“DESTROYING LIVES”

Sanders spoke to a crowd of cheering Verizon workers at a mid-day rally in Brooklyn. “This is just another major American corporation trying to destroy the lives of working Americans,” he said.

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In urging a resumption of talks, Clinton said in a statement, “We rely on these men and women as part of the communications infrastructure that keeps businesses and our economy moving.”

Verizon didn’t appear to be swayed. “Big companies are an easy target for candidates looking for convenient villains for the economic distress felt by many of our citizens,” Verizon Chief Executive Officer Lowell McAdam said in a blog post.

“Contrary to Sen. Sanders’ contention, our proposals do not call for mass layoffs or shipping jobs overseas,” McAdam said.

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Hundreds of Verizon workers protested outside Verizon stores along the East Coast on Wednesday. In New York, strikers chanted “We’re disgusted, union busted” and held placards reading “Against Verizon’s corporate greed.”

“They even want us to move to different states and that’s unfair. How do we take care of our families?” said Anita Long, a 59 year-old telecommunications technician assistant.

“How do you make a billion dollars in one month and tell me you can’t give me a decent wage?” said Long, who has worked at Verizon for 37 years, picketing in Brooklyn.

Verizon and the unions have been talking since last June over the company’s plans to cut healthcare and pension-related benefits over a three-year period.

The workers have been without a contract since its agreement expired in August. Issues include healthcare, offshoring call center jobs, temporary job relocations and pensions.

The last contract negotiations in 2011 also led to a strike. A new contract was reached after two weeks.

On Tuesday, Verizon said it was approached by the Federal Mediation and Conciliation Service. In the last round, the FMCS mediated their contract dispute.

The question of federal mediation is “a diversionary tactic,” CWA’s Master said, adding it has not contacted the FMCS.

“We don’t want to go to Washington ... what is needed is for the company to sit down and address our concerns.”

Verizon’s shares fell 1.3 percent to close at $51.29.