New York City Mayor Bill de Blasio blasted Gov. Andrew Cuomo in an exclusive interview with NY1’s Errol Louis, blasting the governor he says is consumed with “transactional” politics.

“What I found was he engaged in his own sense of strategies, his own political machinations and what we’ve often seen is if someone disagrees with him openly, some kind of revenge or vendetta follows,” de Blasio said of the governor.

The broadsides against Cuomo are the culmination of an increasingly tenuous relationship between the state’s top elected official and the more liberal Democrat who was elected with a wave of progressive support in the city.

The relationship between Cuomo and de Blasio publicly had been one in which the two men carefully sought to avoid any on-the-record critiques, even as the governor was seen as purposefully undermining the mayor on key issues such as an Atlantic Yards land deal, the terms of extending the 421a tax abatement, mayoral control of New York City schools, universal pre-Kindergarten and a city-wide increase in the minimum wage.

De Blasio was likely venting both exasperation with his fellow Democrat, but also demonstrated a willingness to critique a governor who has fallen out of favor with liberal advocates, especially when it comes to economic issues and elected a Democratic-controlled state Senate.

In the interview, de Blasio knocked Cuomo for working to closely with Republican-led Senate at the expense of the Assembly, which is dominated by Democrats from New York City.

“I don’t believe the Assembly had a real working partner in the governor or the Senate in terms of getting things done for the people of this city and in many cases the people of this state,” de Blasio said.

In one stinging rejoinder during the interview, de Blasio took aim at the Cuomo administration’s habit of conducting background briefings and providing anonymous jabs at the mayor and his policies.

“And I want to hasten to say there was some interesting back and forth last week and some unnamed sources well-placed in the Cuomo administration had a few things to say. I’m here in front of you on record saying what I believe,” he said.

De Blasio vented that policy proposals are undermined or in some cases “rejected or manipulated” when he tries to find common ground with the Cuomo.

“I find that to be a lack of leadership because here was an opportunity actually to get something done for people,” de Blasio said.

The mayor is hardly the first Democrat this year to criticize Cuomo, who has been knocked by state lawmakers and city council members for the better part of the year following his re-election last November. But de Blasio is also the most prominent elected Democrat to do so, representing a broader falling out between a governor who is moderate on fiscal issues and a liberal wing of the party that sees itself ascending ahead of the 2016 elections.

Mayors and governors of New York over the last half-century have always had contentious relationships, dating back to Nelson Rockefeller and John Linsday, Ed Koch and Mario Cuomo and George Pataki and Rudy Giuliani.

But both Cuomo and de Blasio insisted they would be different, emphasizing their history together at the Department of Housing and Urban Development and ties to the Clinton wing of the Democratic Party.

In the early days of the de Blasio administration, the mayor sought to carefully cultivate Cuomo as a potentially ally in Albany, where Senate Republicans have been especially hostile to his proposals even before he sought to actively campaign for a Democratic-led majority in the chamber.

De Blasio personally vouched for Cuomo with the labor-backed and liberal Working Families Party, which only 13 months ago openly considered not giving the centrist governor its ballot line. Weeks after the WFP fight, de Blasio endorsed Cuomo for a second term as governor and introduced him as the state Democratic Convention in Suffolk County.

But the era of good feelings do not last, nor did it truly materialize for Cuomo and de Blasio.

This year, Cuomo pushed back against efforts to allow local governments to set their own minimum wage after pledging to back some version of municipal control.

He rejected de Blasio’s call for a permanent extension of mayoral control of New York City schools and initially supported three years before settling on 12 months with the Legislature.

At the same time, Cuomo distanced himself from the mayor’s push to expand affordable housing opportunities under the 421a tax abatement extension, frequently citing the AFL-CIO’s concerns about the lack of a prevailing wage provision for the construction sector.

The mayor was not without his own faults: De Blasio, in turn, had been increasingly frustrated with the byzantine politics of Albany, which he found difficult to navigate.

Adding to the tensions, de Blasio was said to have hired Karen Hinton, the wife of former top Cuomo aide Howard Glaser, without giving the governor a heads up on the appointment.

The bad blood culminated last week, when a Cuomo administration official — who appeared in direct quotes to speak in the recognizable cadence and syntax of the governor himself — blasted the mayor in a background briefing.

“He is more politically oriented in terms of his approach … and then he makes it almost impossible for him to achieve success,” the Cuomo official said, according to The Daily News.

The interview comes just as de Blasio is about to leave the city for a summer vacation through the west and southwest. It airs tonight on NY1’s Inside City Hall at 7 p.m.

Updated: Cuomo spokeswoman Melissa DeRosa responded in a statement.

“For those new to the process, it takes coalition building and compromise to get things done in government,” she said. “We wish the Mayor well on his vacation.”