Union workers are planning for a possible subway slowdown that could hit city trains during the holiday season as they try to ramp up pressure on MTA management amid heated contract talks, The Post has learned.

The latest rumblings of a labor action come as talks between the state-run Metropolitan Transportation Authority and the Transport Workers Local 100 broke up last week without a deal.

TWU members plotting the slowdown are pushing their members to adhere so strictly to contract regulations and work rules that it would make riding New York’s beleaguered trains even more frustrating.

TWU is prohibited by state law from going on strike or otherwise slowing work — and faces severe consequences if it does. In 2005, the union was hit with stiff penalties and other punishment after it launched an illegal strike when talks broke down.

“Since Transit doesn’t respect any soft approach when is the union representatives going to call on us to show who runs NY,” one member posted on a Facebook group populated by TWU members.

On another group, a union leader ticked off steps train operators should follow according to agency rules and advised them to not “worry about the delay in service.”

“Time to begin applying THEIR RULES to the max,” another worker responded.

Labor sources even say that angry workers are floating a possible slowdown on Black Friday, the busiest shopping day of the year.

“Black Friday and Thanksgiving provide leverage points for the rank-and-file transit worker,” said one source. “Workers have reached a boiling point.”

The TWU has been upping its attacks on the MTA’s leadership following three days of tense talks last week, which fell apart on Thursday after TWU rejected a contract offer. Neither party was willing to discuss that deal.

MTA chairman Pat Foye has made labor talks a top priority as his agency confronts budget deficits that could reach $426 million by 2023.

However, in August, union reps rejected an MTA offer that would have increased wages while requiring employees to pay more of their healthcare costs.

Separately, the MTA has also signaled it is examining work rules that critics deride as inefficient and contribute to the agency eye-watering $1.4 billion overtime bill.

TWU International President John Samuelsen — the union’s MTA board rep — denied that workers were deliberately slowing service, but said the phenomenon was an inevitable result of frustration with management.

“When transit workers are angry and demoralized, service suffers,” Samuelsen told The Post. “The patience of transit workers has worn thin.”

“Any effort to delay more than 8 million daily subway and bus customers from getting where they need to go — including work, school, doctors and hospitals — is wholly unacceptable,” said MTA spokeswoman Abbey Collins. “We expect all of our employees to abide by all provisions of the Taylor Law, which expressly bars slowdowns and other types of interruptions impacting transit service.”

She added: “We remain committed to negotiating in good faith.”