ATLANTA – A dispute broke out Thursday between U.S. Sen. David Perdue, R-Ga., and Democratic challenger Jon Ossoff over whether the incumbent supports requiring health insurance plans to cover pre-existing conditions.

Perdue launched a television ad highlighting his commitment to coverage for pre-existing conditions that features his younger sister, Debbie Perdue, a cancer survivor.

“I’ve lived this problem,” she says in the ad. “David’s making a difference for all of us, and anyone who says otherwise doesn’t know my big brother’s heart.”

Perdue is a cosponsor of the Protect Act, Republican-backed legislation introduced last year by Sen. Thom Tillis, R-N.C., supporters say would guarantee health-care coverage for Americans with pre-existing conditions.

But Ossoff’s campaign accused Perdue of siding with other Republicans in efforts to repeal the Affordable Care Act (ACA), legislation then-President Barack Obama steered through a Democratic Congress in 2010 that guarantees coverage for pre-existing conditions.

“Senator Perdue voted at least three times to gut protections for Americans with pre-existing conditions, and last month he said he supports [President Donald] Trump’s Supreme Court lawsuit to overturn the ACA, which would completely destroy protections for pre-existing conditions,” said Jake Best, Ossoff’s press secretary.

PolitiFact, a nonprofit project operated by the Florida-based Poynter Institute, criticized the Protect Act for lacking provisions that would ensure health plans covering pre-existing conditions are affordable.