President Donald Trump took his crusade for tax reform to North Dakota Wednesday.

Though he said the tax reform plan will boost prosperity and make America more competitive during the remarks at the Andeavor Refinery in Mandan, North Dakota, Trump jokingly singled one industry that wouldn’t grow under a reformed and simpler tax code.

“A staggering 94 percent of families need professional help to do their taxes, they have to get it, which is why the tax preparation industry generated $10 billion in revenues last year. That’s one business I want to drive down,” Trump said. “H&R Block will not be supporting Donald Trump.”

He said tax forms can run for 241 pages. But, under his plan, Trump claimed, 95 percent of taxpayers could file on a single page.

“We’re giving hardworking Americans their time back and we’re giving them their money back,” Trump said.

This is the second time in two weeks Trump has taken his push for tax reform on the road. He hit Springfield, Missouri, last week.

“All told, it will be the greatest tax reduction in the history of our country, greater than ever before, so that’s going to be something. You’ll see a rocket ship. You will see something happen like you’ve never seen.”

Trump said the current system punishes companies for investing in the United States and rewards investment abroad.

“Our painful tax system has become a massive barrier to America’s economic comeback. It costs us millions of American jobs, trillions of dollars, and billions wasted on paperwork and compliance. Our tax code is a giant economic self-inflicted wound,” Trump said.

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Capitalizing on his anti-establishment theme, Trump framed the reform as tackling special interests.

“We no longer have to accept a tax code that lets special [interests] win at the expense of the middle class. We no longer have to accept a rigged system,” Trump said. “We talked about that a lot in the campaign.”

Trump earlier called several North Dakota officials to the stage, including Democratic U.S. Sen. Heidi Heitkamp, saying, “Everybody’s saying: What’s she doing up here?” Trump added, “I hope we’ll have your support”

He also called Heitkamp, who flew to her state with Trump aboard Air Force One, “a good woman.”

Then later, as if to add a little more pressure, Trump noted Democrats have backed tax reform before.

“Both of the Reagan tax cuts were passed by a Democratic majority in the House, a Democratic speaker, and a vast majority of Democrats in the Senate, including a Democratic senator from the great state of North Dakota,” Trump said. “So it can happen. Are you listening, Heidi?”