With Republicans on Capitol Hill racing to get a domestic policy mega-bill onto President Donald Trump’s desk, one Massachusetts lawmaker is drilling into the data to show that it’s bad news for a key part of the White House’s base.

Namely, the small business owners who saw a reflection of themselves in Trump in 2024, but since have been buffeted by the Republican’s shifting stance on trade and tariffs.

Now add the deep cuts to Medicaid, the Supplemental Nutrition Assistance Program (widely known as food stamps) and the expiration of tax credits through the Affordable Care Act envisioned by Trump’s “Big Beautiful Bill,” and that’s a big loser for small business owners, according to U.S. Sen. Ed Markey, D-Mass.

In a Thursday letter to U.S. Senate Majority Leader John Thune, R-S.D., and Senate Finance Committee Chairperson Mike Crapo, R-Idaho, Markey noted that 1 in 4 small business owners live in a household that receives health coverage from Medicaid or the Children’s Health Insurance Program, or gets food assistance through SNAP.

Markey was joined in the letter, shared exclusively with MassLive, by U.S. Senate Minority Leader Charles E. Schumer, D-N.Y., and U.S. Sen. Ron Wyden of Oregon, the ranking Democrat on the Senate’s Finance Committee.

“If Republicans gut these programs or allow them to expire, health care costs for small businesses and their families will skyrocket, employees will lose coverage, and entrepreneurs will be stifled. We must expand access to health coverage for all, especially small businesses‚” Markey said in a statement, adding that those same programs are a lifeline for small business owners’ employees and family members.

If it’s approved in its current form, the bill would reduce federal Medicaid spending by $793 billion over 10 years.

Roughly 4.8 million people would be uninsured nationwide by 2034 based on work requirements in a version of the bill approved by U.S. House Republicans, CNBC reported, citing data by the nonpartisan Congressional Budget Office.

In Massachusetts, the bill would cost the state’s health care system $1.75 billion and strip coverage for about 250,000 people, according to Healey’s office.

Trump has been ramping up the pressure for lawmakers to get the bill on his desk.

“To my friends in the Senate, lock yourself in a room if you must, don’t go home, and GET THE DEAL DONE THIS WEEK,” Trump wrote Tuesday on Truth Social. “Work with the House so they can pick it up, and pass it, IMMEDIATELY. NO ONE GOES ON VACATION UNTIL IT’S DONE.”

In their letter to Thune and Crapo, Markey and his colleagues pointed to recent polling data, commissioned by an industry trade group, showing that nearly 7 in 10 small business owners (68%) opposed cutting health care spending while extending tax cuts for the wealthy − which the bill would do if Trump signs it into law.

And more than half (55%) of respondents said they, their employees, or their families rely on the premium tax credits offered through ACA Marketplace coverage.

Sixteen million people nationwide would lose coverage because of the changes the GOP bill makes to the ACA, including those tax credits, according to a KFF analysis.

The survey, conducted from June 9 to June 16, sampled the opinions of 574 small business owners.

“Small businesses succeed when their owners and employees are healthy, secure, and financially stable. Policies that strip away basic support systems in favor of giveaways for the ultra-wealthy don’t just hurt families, they stifle entrepreneurship and economic growth,” the lawmakers wrote. “The Senate reconciliation bill should recognize this and support America’s small business owners and employees.”