The Trump administration has ordered the city to halt all work on a long-planned redesign of 34th Street meant to speed up bus service in Midtown.

In a letter to city and state transportation officials on Thursday, Sean McMaster, administrator of the Federal Highway Administration, wrote that he may withhold federal funding for other projects if the busway moves forward. State officials then said in a statement the work on 34th Street is paused for now. The threat from the federal government is the latest example of administration officials using funding as leverage over local transit projects.

“I demand you cease and desist all activities to implement the 34th Street busway project immediately,” McMaster wrote, citing “potential concerns regarding truck access, and whether the busway can safely and efficiently accommodate large vehicle deliveries.”

McMaster also alleged there is a lack of collaboration between city and state transportation authorities "on this regionally significant project."

The busway plan would restrict passenger vehicles on 34th Street. Similar measures on 14th Street in Manhattan have proved effective at speeding up buses.

The busway is part of a rezoning of Midtown approved by the City Council in August. The project is expected to speed up buses, which crawl at an average speed of 3 mph.

“I fought for the 34th Street busway because it will speed up buses, reduce congestion, and get New Yorkers where they need to go,” Councilmember Keith Powers wrote to Gothamist. “President Trump is once again using his agencies to punish New York City, to the detriment of the everyday New Yorkers who need this busway to happen.“

Federal transportation officials have tangled with New York over congestion pricing, as well as funding for the Second Avenue subway and Gateway project to build a new rail tunnel below the Hudson River.

"New York bus riders suffer the slowest service in America," Danny Pearlstein, spokesperson for the nonprofit Riders Alliance, said in a statement. "Anyone trying to waste more of our time can take a hike."

"The feds should mind their own business. The red paint must go down," he added, referencing the color of dedicated bus lanes.

MTA Chair Janno Lieber called the latest clash another example of “Washington whiplash.”

" I think it's a little bizarre how much they want to get into the day-to-day traffic of New York… Are you going to have to apply to the Secretary of Transportation if you want to have a block party? Is the secretary of DOT gonna decide who gets to sell gyros at which location?” Lieber said. “I mean, it's enough already."

The Federal Highway Administration requested a meeting with city and state transportation officials to discuss how the busway can meet federal standards.

“The vast majority of commuters in Midtown are traveling by transit and they deserve world-class, fast, and reliable buses," city transportation department spokesperson Vin Barone said in a statement. "The redesign for 34th Street mirrors other street designs from across the city and allows for truck, private and emergency vehicle access on every block. We are confident that the design complies with all applicable federal laws and regulations, and we will work with the federal government to advance this critical project.”

The city had planned to implement the busway later this year.

This story has been updated with comment from MTA Chair Janno Lieber and to note the state says the busway work is paused for now.