National Democrats launched digital ads Friday targeting U.S. Sen. Cory Gardner of Colorado over a federal lawsuit aimed at overturning the Affordable Care Act.

The Democratic Senatorial Campaign Committee’s five-figure ad campaign blasts Gardner and other Republican senators in 2020 battleground seats for staying on the sidelines after the Trump administration backed a ruling that declared the federal health legislation unconstitutional.

The Colorado ad notes that when Gardner chaired the Republican Senatorial Campaign Committee he told colleagues that top GOP donors were “furious” that congressional Republicans had been unable to repeal the legislation, known as Obamacare.

“Now, Gardner refuses to oppose a major federal lawsuit to gut protections for Coloradans with pre-existing conditions,” the ad reads. “The same lawsuit would also end other protections like for maternity care coverage and allowing kids to stay on their parents’ insurance until age 26. Cory Gardner’s plan: higher costs, lower quality care.”

Spokespeople for Gardner’s Senate office and campaign committee on Friday didn’t respond to requests for comment from Colorado Politics.

Considered among the most vulnerable GOP senators running for re-election next year, Gardner hasn’t taken a position on the lawsuit, which is making its way through the appeals process after a Texas district judge in December struck down the health care law.

The Trump administration said in March that it agrees with the ruling, which said that 2017 legislation to overhaul the federal tax code voided the health care law.

On multiple occasions, Gardner has declined to tell congressional reporters whether he supports or opposes the lawsuit.

“Senator Gardner is more concerned with pleasing his ‘furious’ donors than fighting for Coloradans – even if it means threatening their health care, from those with pre-existing conditions to families already worrying about the cost of care,” said DSCC spokesman Stewart Boss in a statement.

“After voting again and again to dismantle health care protections for Coloradans and helping pass the reckless tax law that made this suit possible in the first place, Gardner has made it clear that Coloradans can’t afford his dangerous health care agenda.”

The digital campaign runs through the weekend, timed to coincide with the anniversary of the Trump administration agreeing with Republican attorneys general that provisions in the GOP-sponsored tax law renders the health care law unconstitutional.

Other Republican senators targeted by the ads include Sens. Susan Collins of Maine, Martha McSally of Arizona, Thom Tillis of North Carolina, Joni Ernst of Iowa, David Perdue of Georgia, John Cornyn of Texas, Lindsey Graham of South Carolina and Senate Majority Leader Mitch McConnell of Kentucky.

A dozen Democrats are running for the chance to challenge Gardner in next year’s election.