Since President Trump unleashed an on-again, off-again whiplash of global tariffs, congressional Democrats have worked to shine a spotlight on small business owners who say the tariffs and economic toil are threatening their livelihoods.

In videos on social media, local news stories, Capitol Hill news conferences and hearings, Democrats have spotlighted the plight of local entrepreneurs who describe being forced to raise prices, lay off workers, freeze hiring and slow sales to conserve stock as they absorb the impact of Mr. Trump’s trade moves.

It is one way in which Democrats are trying to use the tariff issue in their broader strategy of portraying Mr. Trump and Republicans as catering to the rich and powerful at the expense of ordinary Americans. The focus comes as Democrats work to recast themselves as the party of working people and accuse Republicans, historically known as the party of business, of stifling American entrepreneurship.

“President Trump’s trade war is economic arson on Main Street, and these folks are getting scorched,” Senator Chuck Schumer, Democrat of New York and the minority leader, said at a news conference this week with several small business owners.

“The outcry that we hear from our small businesses echoes what we heard during the early days of the COVID-19 pandemic,” said Representative Nydia M. Velázquez, the top Democrat on the Small Business Committee, at a shadow hearing held on Thursday by House Democrats. “Except this time, the government is causing the pain, not working to alleviate it.”

Democratic leaders have encouraged their rank-and-file members to focus on small businesses. Many of them did so last month when they fanned out across the country during a two-week recess.