To appreciate why U.S. Representative Scott Peters has twice broken with his Democratic colleagues and voted to roll back parts of Obamacare, it’s helpful to know that his San Diego-area district is teeming with voters who have reasons to be angry about the law.

The district has one of the nation’s highest proportions of residents who get health insurance through individual policies, instead of from an employer, and many have learned their policies are being canceled because they don’t comply with the Patient Protection and Affordable Care Act.

Walter Niles is one of them. The self-employed biotechnology consultant with a doctorate in neuroscience was notified in September that his policy was being canceled. The coverage offered through Covered California, his state’s new insurance exchange, has left him unsatisfied.

“I’m paying more and getting less,” said Niles, 59, who leans Republican yet also says he voted twice for President Barack Obama. “It is fundamentally a worse plan.”

The political predicament for Peters, who was elected in 2012 with 51 percent of the vote, illustrates the complicated path ahead for Democrats as they approach the 2014 midterms amid a debilitating Obamacare rollout. Democrats need to gain a net of 17 seats to retake House control, and holding such swing seats as California’s 52nd District are vital to their mission.

Democratic Districts

Yet Peters, 55, and other House Democrats represent more than a third of the districts with above-average proportions of residents who get health insurance through individual policies, Census Bureau data compiled by Bloomberg shows.

Republicans, who represent the remaining two-thirds of districts with higher levels, have been the law’s biggest critics, putting them in sync and sympathy with their constituents who are also complaining about lost coverage.

About 16 million Americans -- roughly 5 percent of the population -- get health insurance through individual policies, the census data show. Though a relatively small segment of the population, their stories of insurance uncertainty draw media attention.

Peters has heard “a lot in the last few weeks about these individual stories of people who for one reason or another have lost the coverage that they thought they were entitled to keep and I think it’s very unfortunate that they had the impression that they could keep it and in fact they couldn’t,” he said in an interview.