In a sharp rebuke of anti-labor policies, Missouri residents on Tuesday overwhelmingly voted down Proposition A, a ballot question that would have prohibited private-sector workers from being forced to pay union dues.

The Missouri General Assembly originally passed Proposition A — which fell into the category of what’s generally referred to as “right to work” laws — in 2017, with Republicans arguing the measure was a critical step in ensuring the state’s economic competitiveness.

Labor organizers at the state and national levels have long argued that allowing workers to opt out of paying fees to a union that bargains on their behalf effectively weakens organized labor. In response to the ballot question, union leaders mounted an aggressive opposition campaign, according to the St. Louis Dispatch, spending upwards of $15 million in ad dollars and even recruiting actor and St. Louis native John Goodman to rally against the law’s passage.

Union leaders celebrated as news of a definitive victory came down Tuesday evening.

“The defeat of this poisonous anti-worker legislation is a victory for all workers across the country,” AFL-CIO President Richard Trumka said in a statement. “The message sent by every single person who worked to defeat Prop. A is clear: When we see an opportunity to use our political voice to give workers a more level playing field, we will seize it with overwhelming passion and determination.”

Sen. Bernie Sanders (I., Vt.), a longtime supporter of organized labor, tweeted his support of Proposition A’s defeat.

“Right-to-work legislation must be defeated nationwide,” Sanders wrote. “We must stand together, beat back union busters and continue to build and grow the trade union movement in this country.”

The vote to kill the anti-labor measure comes at a time when unions find themselves embattled at the federal level. The Supreme Court on June 27 ruled on the landmark Janus v. AFSCME case, which called into question the right of 22 states to charge “agency fees” to any workers benefitting from a union’s collective bargaining. In a 5-4 vote, the court’s conservative justices ruled that forcing government workers to subsidize union activity violates their First Amendment rights.

The decision poses a big problem for union leaders, members, supporters and Democrats, the latter of whom fear a substantial drop-off in union fees could mean a significant hit in political contributions.

However, Tuesday’s landslide rejection of Proposition A — like the wave of momentum from teachers’ unions in red states that preceded it — is proof that in some parts of America, if not in the White House, support for organized labor is alive and well.