Booming windmill industry hits a snag 

He’s called them “disgusting” and “ugly” and “stupid,” denouncing them in hundreds of anti-wind tweets and public comments dating back more than a decade, when he tried and failed to block a wind farm near his Scottish golf course.

And those turbine blades. “They say the noise causes cancer,” Trump told a Republican crowd last spring, in a claim immediately rejected by the American Cancer Society.

Now, wind industry leaders and supporters fear that the federal government, under Trump, may be pulling back from what had been years of encouragement for climate-friendly wind.

The Interior Department surprised and alarmed wind industry supporters in August, when the agency unexpectedly announced it was withholding approval for the country’s first utility-scale offshore wind project, a $2.8 billion complex of 84 giant turbines. Slated for building 15 miles off Martha’s Vineyard, Vineyard Wind has a brisk 2022 target for starting operations. Its Danish-Spanish partners already have contracts to supply Massachusetts electric utilities.

Investors backing more than a dozen other big wind farms are lined up to follow Vineyard Wind with offshore wind projects of their own. Shell’s renewable-energy offshoot is among the businesses ponying up for federal leases, at bids of more than $100 million, for offshore wind farm sites.

The Interior Department cited the surge in corporate interest for offshore wind projects in saying it wanted more study before moving forward. It directed Vineyard Wind to research the overall impact of the East Coast’s planned wind boom.

Interior Department spokesman Nicholas Goodwin said offshore energy remains “an important component” in the Trump administration’s energy strategy. But the strategy includes “ensuring activities are safe and environmentally responsible,” Goodwin said in a statement.

Wind power now provides a third or more of the electricity generated in some Southwest and Midwest states. And New York, New Jersey and other Eastern states already are joining Massachusetts in planning for wind-generated electricity.

Along with the U.S. shale oil boom, the rise in wind and solar is helping cushion oil supply shocks like the recent attack on Saudi oil facilities.

But the Interior Department’s pause on the Vineyard Wind project sent a chill through many of the backers of the offshore wind boom. Critics contrast it with the Republican administration’s moves to open up offshore and Arctic areas to oil and gas development, despite strong environmental concerns.

“That I think is sort of a new bar,” for the federal government to require developers to assess the impact of not just their projects but everyone’s, said Stephanie McClellan, a researcher and director of the Special Initiative on Offshore Wind at the University of Delaware. “That worries everybody.”

Thomas Brostrom, head of U.S. operations for Denmark’s global offshore wind giant Orsted and operator of the pioneering Block Island wind farm, said that “the last three, four years have seen unbelievable, explosive growth, much more than we could have really hoped for,” in the U.S., compared to Europe’s already established wind power industry.

Given all the projects in development, “we hope that this is a speed bump, and certainly not a roadblock,” Brostrom said.