Mayor Bill de Blasio’s $2.7 billion streetcar plan to connect the Brooklyn and Queens waterfronts appears headed on a road to nowhere.

Reps from the city’s Department of Transportation and Economic Development Corp. testified before a City Council task force Thursday that the Brooklyn-Queens Connector, or “BQX” project, likely hinges on roughly half its construction funding coming from the federal government and the state-run Metropolitan Transportation Authority providing streetcar riders free transfers to and from subways and buses.

One huge problem: both are far from locks with the project’s environmental review set to begin this fall.

Councilman Jimmy Van Bramer (D-Queens) questioned “how committed” the de Blasio administration is to driving the trolley plan to the finish line when it’s banking on White House support– especially considering President Trump’s volatile relationship with City Hall.

“How do you plan to overcome that barrier if we continue to have a hostile occupant in the White House?” he asked.

“I don’t pretend to be an expert on the Trump administration or Washington DC,” responded Seth Myers, an executive vice president for EDC. “Obviously, there are many challenges there. We have a lot of merits for the project, and we will continue our conversations with them.”

When pitching the project in 2016, de Blasio boasted it would pay for itself by taking a percentage of property taxes on nearby real estate ventures. However, this so-called “venture capture” strategy” is now only expected to raise $1.3 billion for BQX construction, officials said.

Meanwhile, projected construction costs have risen by $200 million, from $2.5 billion to $2.7 billion, even though the planned route – which runs from Red Hook, Brooklyn to Astoria, Queens – was reduced in size last year from 16 miles to 11 miles, in part by cutting out a stop in Sunset Park.

City Hall also now hopes to have the BQX running by 2029 instead of its original 2024 projection.

Afterwards, Myers refused to respond to a reporter’s question on whether the project is a pipe-dream without the feds and Metropolitan Transportation Authority on board.

Christopher Hrones, DOT’s director of strategic transit initiatives, told the Council’s BQX task force that “fare integration with MTA, including free transfers” is “an essential component of making the BXQ a success.”

He later confirmed to reporters that the MTA has made no such commitment but is hopeful “it will happen” so that BQX commuters wouldn’t be charged twice for using mass transit as NYC Ferry riders are when they continue routes on subways and buses.

“This project will need to do that in order to be successful,” Hrones added.

An MTA spokesman said,“Fare matters are discussed and decided by the MTA board after a public hearing process. We’re in touch with the DOT and monitoring the developments of the BQX proposal.”

During the hearing, task force members also raised other concerns, including rising project costs and whether the BQX would gentrify waterfront neighborhoods by driving out longtime residents and merchants to the benefit of real estate developers whose property values would be expected to soar.

“What [is] most telling is the cost … when we could get potentially faster bus [service] cheaper,” along the same route, said Councilman Carlos Menchaca (D-Brooklyn), who chairs the task force and district includes Red Hook and Sunset Park.