The union that reps transit workers workers launched a scathing ad and flier campaign today targeting Mayor Bill de Blasio for how much the city will contribute to the MTA's capital plan, which funds big projects like the Second Avenue Subway.

"The city invested $2.4 billion for the beautiful, new one-stop extension to the No. 7 line," reads the TWU Local 100 ad."That's great for the lucky few going to the far West Side of Manhattan, and the even luckier fat cat developers and real estate interests who stand to get rich on high-rise luxury towers and hotels."

The ad then criticizes City Hall for not agreeing to cover 10% of the state-run MTA's capital plan, which pays for big projects like the Second Avenue Subway, and says 90% of MTA rides are in New York City. A state review board has to approve $26.8 billion of the plan, which isn't paid for by bridge and tunnel tolls.

TWU Local 100 said the print ad would run in amNewYork and the Daily News, and that transit workers would also hand out 100,000 fliers at subway terminals and depots citywide over three days. The union represents 40,000 workers and is the largest local transit union nationally.

"We're doing this because we believe the city of New York is shortchanging the MTA's capital budget," said its head John Samuelsen. "The potential for derailments goes up dramatically if the capital budget isn't funded."

de Blasio has said the new No. 7 train station benefits include 5,000 new affordable apartments, as well as more than 20,000 new jobs that have been created so far, most living-wage.

"Those are the kind of numbers that change people's lives, and change the economy of this city," he said at the No.7 train station opening on Sunday.

The MTA politicized the G train subway derailment in Brooklyn last week, which injured two riders when a bench wall collapsed. Chairman Thomas Prendergast said he was tired of writing letters to city officials about capital funding, and that the next plan has almost $1 billion for repairs to subway structures like bench walls.

Earlier this year, the MTA asked City Hall for almost $660 million earlier this year, then stepped it up to $3.2 billion. The state has pledged $8.3 billion to fill the deficit, but has not said where the money will come from.

The MTA's financial woes are the latest source of division between Gov. Andrew Cuomo and de Blasio, who have been at odds throughout the mayor's first term.

"The state should not be recruiting surrogates to attack the city when such serious issues are at stake," said mayor's office Amy Spitalnick.

"The city fully met the MTA's funding request this spring, providing the largest general capital contribution to the state authority in recent history, only to have the MTA turn around the same day and ask for billions more."

She also said that the state has raided the MTA's money to fill other budget holes in the past.