If media outlets paid even minimal attention to the struggles of working people, and to the organizations that represent them in those struggles, the last few days on the New York City campaign trail would have been recognized as a significant turning point in the 2016 presidential race: when a candidate for the Democratic presidential candidate backed striking workers so aggressively that he sparked a clash with some of the nation’s most powerful corporate CEOs.

On Wednesday morning, in New York, one of the city’s oldest and politically engaged union locals gave Vermont Senator Bernie Sanders its enthusiastic endorsement. “In Bernie Sanders, we see a kindred spirit,” Transport Union Workers Local 100 President John Samuelsen told 300 transit workers who attended a Brooklyn rally to announce the endorsement by the legendary union local, which represents roughly 40,000 workers and tens of thousands of retirees. “Bernie Sanders has been fighting against the ‘powers that be’ in this country on behalf of all American workers his entire life. That’s what this country needs. That’s what American workers need. A true champion of our cause!”

Shortly after he accepted the TWU endorsement, Sanders was championing the union cause on a picket line with striking Verizon workers. “I know your families are going to pay a price,” Sanders shouted as the workers cheered. “On behalf of every worker in America who is facing the same kind of pressure, thank you for what you’re doing. We’re going to win this thing!”

Sanders has been endorsed by the Communications Workers of America, one of the unions representing the 39,000 Verizon landline and cable employees who walked off the job on Wednesday in a critical fight to ensure that workers get a fair share in the digital economy. Sanders’s rival for the Democratic nomination, former secretary of state Hillary Clinton, has received a number of important union endorsements, including those of the National Education Association, the American Federation of Teachers, the Service Employees International Union, and, just this week, Local 3 International Brotherhood of Electrical Workers in New York. On Wednesday, Clinton showed support for the Verizon strikers and her campaign issued a statement in which Clinton said she was “disappointed” that negotiations between Verizon and its unions had broken down.

But it is the aggressiveness with which Sanders defended worker rights while on the campaign trail that attracted attention—not just from workers but from corporate CEOs.

Verizon CEO Lowell McAdam ripped Sanders for joining the CWA picket line and echoing union concerns. In a statement headlined “Feeling The Bern of Reality—The Facts About Verizon and The Moral Economy,” the CEO decried the senator as “uninformed,” and claimed that Sanders’s pro-labor stance “oversimplifies the complex forces operating in today’s technologically advanced and hyper-competitive economy.”

The assault on Sanders by McAdam was similar to an attack on the senator by General Electric CEO Jeffrey Immelt, who objected to a recent suggestion by the senator that the greed of corporations such as GE—which have shipped thousands of jobs overseas—is undermining the middle class and “destroying the moral fabric” of the United States. The GE CEO wrote an opinion piece titled, “Bernie Sanders says we’re ‘destroying the moral fabric’ of America. He’s wrong.”

That earned a response from leaders of the United Electrical, Radio, and Machine Workers of America, who wrote: “As officers of a national union that has represented GE workers for 80 years, we can affirm, from our union’s experience and knowledge of GE, that Mr. Sanders is right.”

“Since 1999, GE has reduced its U.S. workforce by 37 percent, and since 2008 the company has closed more than 50 factories and facilities in the United States,” explained UE officers Peter Knowlton, Andrew Dinkelaker, and Eugene Elk. “In 1995, 68 percent of GE’s total employment was in the United States; by 2015 it was 38 percent. For a decade, GE has pursued a policy it calls the ‘competitive wage,’ aimed at cutting the wage rates of its manufacturing workers in half, even as the pay of Mr. Immelt and other executives soars higher into the stratosphere.”

For his part, Sanders seemed to be relishing the “Which Side Are You On?” struggle, as he has frequently during the course of a campaign that has seem him join union picket lines and criticize CEOs in a number of caucus and primary states. After Verizon’s McAdam decried the senator’s pro-union rhetoric as “contemptible,” Sanders tweeted: “I don’t want the support of McAdam, Immelt and their friends in the billionaire class. I welcome their contempt.”

That was an echo of the great line from President Franklin Delano Roosevelt, who famously declared on the campaign trail in New York in 1936, when he was taking hits from bankers and CEOs who did not like the New Deal: “They are unanimous in their hate for me—and I welcome their hatred.”