Democratic socialist presidential hopeful Bernie Sanders won the most votes in both Iowa and New Hampshire, but has seen support crater in areas with a high proportion of residents on private health insurance.

A Washington Free Beacon analysis of census data and early primary results found that Sanders finished no higher than third and as low as fifth in the three Iowa counties with the highest proportion of privately insured adults. In New Hampshire's Rockingham County, where 83 percent of adults have private insurance, Sanders lost by 4 points to former South Bend, Ind., mayor Pete Buttigieg and nearly dropped to third behind Sen. Amy Klobuchar (D., Minn.).

Sanders has campaigned on a Medicare for All proposal that would end private health insurance. His failure to succeed in areas with high concentrations of privately insured voters reinforces concerns that the Vermont senator could undermine down-ballot Democrats in the general election. Suburban districts key to the House majority also hold high proportions of privately insured adults. Democratic candidates across the country are retreating from Medicare for All even as Sanders emerges as the frontrunner in a crowded primary field.

The proposal also threatens to alienate a key liberal constituency, as labor unions push back against the elimination of health insurance benefits they negotiated with employers. As the presidential field moves on to Nevada, the state's politically powerful Culinary Union has rejected Medicare for All. The union released a flyer Tuesday saying Sanders would "end Culinary health care" if elected.

Sanders repeatedly cited Medicare for All as a reason for his victory in New Hampshire, expressing confidence that "people will be very supportive" of the policy. An analysis of results in early primary states suggests that Medicare for All could hurt the Vermont senator in key 2020 counties.

In addition to losing New Hampshire's Rockingham County, Sanders also struggled in Hillsborough and Merrimack counties, where close to 80 percent of adults have private health insurance. He won those counties handily in his 2016 primary, beating Hillary Clinton by 15 and 19 points, respectively. Sanders took both Hillsborough and Merrimack by just 1 point in 2020.

Sanders's shortcomings in Rockingham, Hillsborough, and Merrimack could present President Donald Trump an opportunity to flip the Granite State in November after losing by just 0.4 percent in 2016. More than 64 percent of the state's population resides in the three counties. Trump won Hillsborough, home to one-third of the state's population, by fewer than 500 votes in 2016. A stronger showing in the county of more than 400,000 could be enough to tip the scale against Sanders in November.

Hillsborough and Merrimack counties fall in the state's Second Congressional District. The district's representative, Democrat Chris Pappas, refused to endorse Medicare for All.

The Vermont senator's struggles in areas with high proportions of private health insurance also affected the Iowa caucuses. Sanders lost by an average margin of nearly 18 points in Dallas, Winneshiek, and Bremer counties, which have the highest proportion of privately insured adults in the state. Sanders's support dropped 35 points in Winneshiek, where the Vermont senator beat Hillary Clinton by double digits in 2016. He finished third behind Buttigieg and Klobuchar in 2020. He finished fourth and fifth in Dallas and Bremer, respectively.

Iowa counties with high private insurance rates also fall in potentially vulnerable House districts held by Demcorats. Dallas County is in Iowa's Third Congressional District, which leans Republican and voted for Trump in 2016. The state's First Congressional District, which leans Democrat but backed Trump in 2016, also includes Winneshiek and Bremer counties. The districts' respective representatives, Democrats Cindy Axne and Abby Finkenauer, both narrowly defeated incumbent Republicans in 2018 and have not supported Medicare for All.

Pappas, Axne, and Finkenauer's reluctance to embrace the policy is in keeping with contentious House races across the country. Democratic congressional candidate Jill Schupp, who is challenging GOP representative Ann Wagner in Missouri's suburban Second Congressional District, is backpedaling from Medicare for All despite previously endorsing the policy as a state legislator. Kentucky Senate hopeful Amy McGrath has followed suit in her race against Senate Majority Leader Mitch McConnell (R., Ky.). McGrath came out against Medicare for All in an ad released Tuesday, though she previously called a single-payer health care system "the way to go."

Chris Pope, a health care expert at the conservative-leaning Manhattan Institute, said Democrats in swing districts are justified in distancing themselves from Sanders's signature proposal.

"Democrats are going to be forced to answer questions like, ‘Do you really support the tax increases that are necessary for [Medicare for All]? Do you really support banning private insurance? Do you really support what Bernie's threatening to do to your local hospitals, revenue insolvency?' These are all going to be really big, unpleasant questions for a lot of Democrats," Pope said.