Even as many Republicans continue to back a repeal of the Affordable Care Act, a majority of GOP voters want to retain a core consumer protection of the law that prohibits insurers from denying care or charging more to people with histories of health problems, according to a poll released Wednesday.

The requirement that insurers treat people with preexisting conditions the same as those with pristine health histories allowed the law to expand coverage to millions of previously uninsurable people starting in 2014.

But the Trump administration has refused to defend it in a legal challenge against the law brought by 20 Republican state attorneys general. The administration called for the protections guaranteeing coverage to be nullified.

The poll from the Kaiser Family Foundation showed 7 in 10 people think insurance companies should not be permitted to deny coverage because of a person’s medical history or charge them higher rates. Support for the preexisting conditions provision included 58 percent of Republicans. (Kaiser Health News is an editorially independent program of the foundation.)

As the 2018 congressional elections near, Democratic and independent voters identify health care as “the most important issue” for candidates to discuss. Support for the provision is especially strong among households where someone has a preexisting condition. But it remains a second-tier priority for Republican voters, according to the poll, nearly tied with immigration and behind the economy and jobs. Nearly 6 in 10 Republican voters place a priority on a candidate’s support for repealing the health law.

There is more partisan agreement on President Donald Trump’s proposal to require that drugmakers publish list prices for their drugs in television commercials. Three-fourths of the public support the idea.

Those drug ads are ubiquitous on TV, and 14 percent of people who said they saw an ad said they had talked with a doctor about the specific medicine, the poll found. More than half said the physician gave them the drug and 48 percent said they discussed the cost of the medicine with the doctor.

The poll was conducted June 11-20 among 1,492 adults. The margin of error is +/-3 percentage points for the full sample.