Be careful what developer Steve Ross wishes for.

With just days to go until the June 22 primary, a super PAC backed by the billionaire real estate developer is flooding city council races with spending on opposition media, targeting a slate of progressive candidates whose platforms include strong support for sustainable transportation.

The group, called Common Sense NYC, has spent more than $270,000 on mailers and digital advertising attacking five Democratic council candidates endorsed by StreetsPAC, a political action committee that supports candidates that are pro-safe-streets and pro-mass-transit. Common Sense NYC has also spent more than $316,000 to support 12 council candidates not endorsed by StreetsPAC, city campaign finance data shows.

Common Sense NYC has also put some money behind candidates who received StreetsPAC’s endorsement and against others who didn’t. But that spending has amounted to far less and gone to fewer candidates.

The super PAC’s primary funder is Ross, the chairman and founder of Related Companies, a major real estate developer that owns and manages Hudson Yards.

A quick look at Common Sense’s mailers make clear that the group is not targeting the progressive candidates because of their support for better mass transit, bike and pedestrian infrastructure, but because of their broader progressive agendas.

“Warning! Jaslin Kaur is APPROVED by the SOCIALISTS THAT THREATEN PUBLIC SAFETY, DESTROY OUR COMMUNITIES AND RAISE TAXES,” reads one particularly subtle mailer targeting a StreetsPAC-endorsed candidate in eastern Queens.

Indeed, Common Sense NYC Treasurer Jeffrey Leb said the group’s “opposition to these candidates has nothing to do with their transportation platforms.”

“We oppose them because they’re not objectively qualified to hold public office for a variety of reasons including the fact that they are Socialist candidates who would defund the police while violent crime is soaring,” Leb added.

Nevertheless, if Common Sense NYC’s deep-pocketed effort to thwart these candidates is successful, the result would be fewer lawmakers on the City Council who are keen on expanding transit and better serving those who bike and walk, the targeted candidates said.

“It’ll really damage so many of the inroads we’ve made already, like say with the Flushing Busway and as well as with the Eastern Queens Greenway,” said Kaur, who has faced more than $61,000 in opposition spending from Common Sense NYC. “It’ll continue to make our city more inaccessible.”

Common Sense NYC’s focus on candidates like Kaur likely has more to do with their opposition to massive luxury development projects — like the kind Ross undertakes — than with transportation, said Eric McClure, StreetsPAC’s executive director.

“For the most part over the past decade or so, I think real estate interests have been generally supportive of remaking the streets of this city,” he said. “They get the value of safer streets and things like bike lanes and bike parking.”

But perhaps not in every corner of the city, said John Choe, another Queens council candidate who was endorsed by StreetsPAC and has been targeted by Common Sense NYC.

“We have a lot of developers and their allies on the community board here who have been resisting any change to the street layouts, taking any space from parking and driving of private vehicles, and resisting calls for improving public transit, including buses and subway access here,” said Choe, who has faced more than $54,000 in opposition spending from Common Sense NYC. “That’s going to be I think one of the reasons why there’s been such a huge push back, because many of us have been very vocal advocates on these issues.”

For Christopher Marte, a council candidate in Lower Manhattan, Common Sense’s attempt to thwart candidates like him may be a sign they’re doing something right.

“We knew that us running a really good campaign and actually being the front-runner, that we were going to be targeted by ultra-developers,” he said. “We kind of expected the guy that developed Hudson Yards to come after us.”

The election is on June 22. Early voting continues through 4 p.m. Sunday. Click here for more information.