Senior Republican Senator Chuck Grassley of Iowa publicly rebuked President Donald Trump's unsubstantiated claim that wind turbines are linked to cancer, calling it "idiotic."

Trump, who has long attacked wind power and frequently fought against wind turbines being built near the golf courses he owns, made the claim at a Republican fundraising event on Tuesday.

Researchers who have studied the issue have found no evidence that wind turbines directly cause any physical illness.

This past February, a Scottish court ruled against Trump in his effort to stop the government from building wind turbines near his Aberdeen, Scotland golf course, ordering him to pay the government's legal costs.

Senior Republican Senator Chuck Grassley of Iowa publicly rebuked President Donald Trump's unsubstantiated claim that wind turbines are linked to cancer, calling it "idiotic" to Iowa reporters on Wednesday.

Grassley said Trump's "comments on wind energy — not only as a president but when he was a candidate — were, first of all, idiotic, and it didn’t show much respect for Chuck Grassley as the grandfather of the wind energy tax credit," he told the Des Moines Register.

Trump, who has long attacked wind power and frequently fought against wind turbines being built near the golf courses he owns, laid into the wind industry at a Republican fundraising event on Tuesday.

"If you have a windmill anywhere near your house, congratulations your house just went down 75% in value. And they say the noise causes cancer, you tell me that one, OK?," Trump claimed, citing no proof for the assertion that windmills cause cancer.

Researchers who have studied the issue have found no evidence that wind turbines directly cause any physical illness.

Read more: Trump claimed wind turbines cause cancer, reigniting a long-running hate campaign against wind power with a weird conspiracy theory

This past February, a Scottish court ruled against Trump in his effort to stop the government from building wind turbines near his Aberdeen, Scotland golf course, ordering him to pay the government's legal costs.

Trump's comments garnered significant mockery and criticism including that of Grassley, a top Senate Republican who has supported many of Trump's initiatives.

Iowa is a national leader in wind power, ranking second nationwide in wind energy production and deriving more than 30% of its total energy from wind, according to the Iowa Farm Bureau. After Trump's comments, Grassley re-started a bipartisan effort to secure more federal funding for wind energy, the Des Moines Register reported.

Some Republicans, however, have avoided directly challenging Trump's assertion. Iowa's Republican Governor Kim Reynolds said it "wasn't her place" to decided whether wind turbines cause cancer, telling the Des Moines Register, "you know how those things change, one year, coffee’s good for you. The next year, coffee causes cancer."

And White House strategic communications chief Mercedes Schlapp said she "didn't have an answer" as to whether turbines were linked to illness.