In this March 16, 2019, photo, Democratic presidential candidate Sen. Bernie Sanders, I-Vt., speaks at a rally in Henderson, Nev. (AP Photo/John Locher)

(CN) — Senator Bernie Sanders, who has said he intends to run the first unionized presidential campaign in history, announced Monday a policy proposal sure to resonate with that base: banning right-to-work laws.

“When billionaires like the Koch brothers spend millions of dollars successfully lobbying for so-called ‘right to work’ for less laws, they are waging a war on workers,” the Vermont senator said at a Las Vegas speech to the International Association of Machinists.

Just more than half of U.S. states currently have some form of law on the books banning unionized workplaces from negotiating contracts which require all members who benefit from a union contract from paying dues.

Premised upon the 1947 Taft-Hartley Act, such laws can now be found in 28 states and Guam, and they have spread with heavy lobbying from the U.S. Chamber of Commerce and prominent Republican donors.

“When we are in the White House, we are going to pass the Workplace Democracy Act that I will be re-introducing in the Senate,” Sanders said.

The Taft-Hartley Act restricted the power and activity of labor unions, and the legislation backed by Sanders targets the statute within it allowing states to pass laws banning agency fees.

In a huge blow to organized labor last year, a sharply divided Supreme Court ruled in Janus v. AFSCME that government-employee unions could not force nonmember workers to pay bargaining fees.

“This year we have seen a right-wing think tank try to follow the disastrous Janus decision with another court case that could essentially impose right-to-work on the airline industry,” Sanders told the machinists, who have been protesting nationwide for favorable terms in their ongoing negotiations with American Airlines. “In a Bernie Sanders administration, that will never, ever happen.”

The mandatory fees banned by the Janus decision had been allowed for more than four decades under the 1977 Supreme Court precedent Abood v. Detroit Board of Education, which Justice Samuel Alito overruled as a violation of the First Amendment right of association.

In a dissent, Justice Elena Kagan wrote ruefully: “The First Amendment was meant for better things.”

“It was meant not to undermine but to pro­tect democratic governance—including over the role of public-sector unions,” she wrote at the time.

President Donald Trump, however, celebrated that decision last July.

“Supreme Court rules in favor of non-union workers who are now, as an example, able to support a candidate of his or her choice without having those who control the union deciding for them,” he tweeted at the time. “Big loss for the coffers of the Democrats!”

Boasting a $28 million war chest, Sanders has touted his ability to fundraise based on small donors. His campaign reported that its average donation was $20, even more modest than the $27 figure that was his rallying cry three years ago, but the senator’s persistent delay in releasing a decade’s worth of tax returns has drawn scrutiny toward his finances.

Sanders has since promised to release those returns after the April 15 tax filing deadline.