The progressive health care advocacy group Save My Care launched a digital ad campaign Monday morning targeting Sen. Dean Heller (R-NV) over his sponsorship of a new Obamacare repeal bill that would make deep cuts to Medicaid.

Save My Care will not disclose the size of the ad buy, but told TPM it will target independent voters in Nevada on Twitter, Facebook, and other platforms.

The ad features a cancer patient and cites a new study by the Center on Budget and Policy Priorities finding that the bill co-sponsored by Heller would allow states to waive some of Obamacare’s protections for people with pre-existing conditions.

Earlier this summer, Heller opposed two Senate bills that would have repealed the Affordable Care Act and ended the Medicaid expansion that his state and others have used to cover hundreds of thousands of low-income residents, but he voted for a so-called “skinny repeal” bill that Nevada’s Republican governor strongly opposed.

Heller, arguably the most vulnerable Republican senator up for reelection next year, was hit with attack ads from both sides during this health care fracas. A pro-Trump outside group went after him in TV ads for being insufficiently loyal to the president’s agenda, and one of his Democratic challengers ran ads calling for Heller to be “repealed and replaced” over his final vote.

Last week, Heller joined with Sens. Lindsey Graham (R-SC), Bill Cassidy (R-LA) and Ron Johnson (R-WI) on a new bill that would scrap Obamacare’s employer and individual mandates and the medical device tax, and convert federal funding for Medicaid and the health care exchanges into block grants that states could spend however they choose, with essentially no limits.

The Center on Budget and Policy Priorities estimates that Nevada would lose $639 million in federal funding by 2026 under the proposed bill.