The state’s second-largest public workers union on Thursday endorsed Zephyr Teachout’s insurgent Democratic primary campaign for governor over incumbent Andrew Cuomo.

“The Public Employees Federation endorsement is an act of courage and bravery by workers who have a lot at stake,” said Teachout campaign manager Mike Boland. “Today they rose above the culture of fear that is pervasive in Albany under Governor Cuomo. The Governor and his old boys club better watch out, this challenge is serious and it isn’t going away.”

Updated: In a statement, PEF President Susan Kent said the endorsement was a “testament” to the democratic nature of the union.

“PEF is a very democratic union and today is a testament of that,” said PEF President Susan M.Kent. “This union has taken a bold step to endorse Zephyr Teachout and Tim Wu for the office of Governor and Lt. Gov. of New York state. They are the leadership this state needs, that public workers need, and the citizens of the state of New York that we serve.”

Cuomo and PEF, a union of mostly white-collar workers, have not had the best relationship.

The union did wind up endorsing Cuomo’s first bid for governor in 2010, while other large public-sector labor groups did not.

The New York State United Teachers Union, meanwhile, issued no endorsement earlier today in the race for governor.

Both NYSUT and PEF had met with Teachout, as well as Green Party candidate for governor Howie Hawkins.

Cuomo, however, sought a less generous contract from PEF and other labor unions, while also pushing through a new, less generous pension tier.

The labor actually rejected the proposed contract, but under the threat of layoffs backed an altered, revenue-neutral agreement.

PEF rank-and-file members booted its leadership, which was seen as too close to the administration, with newly installed president Susan Kent promising a harder line with the governor’s office.

News of the endorsement, first reported by Rick Karlin of the Times Union, comes as Cuomo’s re-election campaign has sought to remove Teachout, a Fordham law professor, from next month’s primary ballot on the grounds she does not meet the state’s five-year residency requirement.

A state Supreme Court judge in Brooklyn ruled in favor of Teachout, but Cuomo lawyer Marty Connor has indicated plans to appeal.