Though both parties have sought to lower the top corporate tax rate in the last decade — President Barack Obama proposed lowering it from 35 percent to 28 percent — Republicans in 2017 pushed it down to 21 percent, in addition to expanding some generous tax breaks. The new law allowed immediate expensing of capital expenditures, for example, in order to goose investment. That was one of the primary reasons that more corporations paid no federal taxes, according to the report.

Mr. Trump and his Republican allies argued that the tax changes would stimulate investment and economic growth. That has happened, though not by as much as they predicted.

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Here in Ohio, even though unemployment has hit an 18-year low, several counties still have jobless rates significantly higher than the national rate, 3.8 percent, and the statewide rate, 4.4 percent. Ohioans have witnessed so many factory closures over the years that they seem to live with a permanent sense of economic wariness. The question for Democrats is how to leverage that to their advantage as they try to retake the state, which Mr. Trump won by 8 percentage points in 2016.

David Betras, the Democratic chairman in Mahoning County, a traditionally blue stronghold of union voters that President Trump nearly carried in 2016, said that Democrats had not yet figured out how to use the economic angst of laid-off employees and minimum-wage workers to defeat Mr. Trump in Ohio in 2020.

“Believe it or not, if you listen to the president, he addresses that issue,” Mr. Betras said. “He does it with a lot of smoke and very many mirrors, but he’s at least talking about how good the economy is and what I’ve done for you. ‘I’m with you. I have your back.’”

Even as candidates focus on corporate taxation, Mr. Betras said the issue didn’t resonate with voters in the same way as more familiar topics like health care or immigration. (Mr. Betras, a lawyer, has endorsed Representative Tim Ryan of Ohio for the Democratic nomination.)