Trump was talking up his support for coal during his speech in Cedar Rapids on Wednesday when he said: “I don’t want to just hope the wind blows to light up your homes and your factories.” He added “as the birds fall to the ground,” a reference to birds killed by turbines.

The remark drew some cheers and laughs inside the arena but didn’t go over well across Iowa, where the rapid growth of the state’s wind energy industry has been a bipartisan success story. Environmentalists and politicians said the president’s suggestion that wind is unreliable was outdated and off-base, and noted that bird deaths have been minimized and aren’t a source of controversy in Iowa.

Democratic gubernatorial candidate Andy McGuire called Trump’s comment “an attack on Iowa’s economy.” Iowa Environmental Council executive director Ralph Rosenberg called the president “inaccurate and misinformed.”

Iowa’s senior Republican senator, U.S. Sen. Chuck Grassley, who is considered the father of the federal wind production tax credit that has subsidized the expansion of the industry since the 1990s, again vowed to oppose any anti-wind policies Trump might pursue.

Through a spokesman, Grassley reiterated his year-old pledge that Trump would succeed in ending the wind production tax credit in Congress “over my dead body.” Last month, Grassley took issue with a study ordered by Energy Secretary Rick Perry into the reliability of the electric grid, saying he believed it was meant to undermine wind. Grassley argued that Iowa’s utilities have proven wind can be dependable.

In the most ever for any state, Iowa last year generated 36.6 percent of its electricity from wind. That figure is expected to keep growing, with the state’s two largest utilities having already started $4 billion in additional wind expansion projects.

Des Moines-based Mid American Energy, a leader in wind, said that using a balanced mix of traditional and renewable energy sources allows the company to deliver power to customers regardless of whether the wind blows.

MidAmerican says its adoption of wind has helped make its rates among the lowest in the nation. That has also made Iowa an attractive state for companies that use lots of power but want it to be clean. Microsoft, Facebook and Google have each built large data centers in Iowa in recent years.

A recent state report says 6,000 Iowa workers are employed in the wind energy industry, including those who manufacture and install wind turbines. Farmers also benefit from receiving payments for leasing their land to host them.

“Wind has been a great story in Iowa in every aspect,” said Josh Mandelbaum, an attorney in Des Moines for the Environmental Law and Policy Center. “For everyone else who has looked at this — policymakers across the political spectrum — all those things make supporting wind a no-brainer.”