Republicans may have found their new ad-makers at CNN’s Democratic debate in Detroit.

On Tuesday night, four centrist presidential candidates launched into the types of attacks that can be weaponized by the GOP opposition.

“I think Democrats win when we run on real solutions,” former Rep. John Delaney (D-MD) told Sen. Elizabeth Warren (D-MA), whose progressive policy proposals have become a cornerstone of her campaign. “When we run on things that are workable, not fairy-tale economics.”

Warren was quick to snap back at the millionaire businessman: “I don’t understand why anybody goes to all the trouble of running for president of the United States just to talk about what we really can’t do and shouldn’t fight for. I don’t get it.”

Delaney was just one of several moderates, including Rep. Tim Ryan (D-OH), former Colorado governor John Hickenlooper, and Montana Gov. Steve Bullock, who cautioned their fellow Democrats against going big.

Bullock, who made his debut debate appearance in Detroit, criticized Warren on the issue of immigration.

“We need to expand legal immigration, we need to create a path for citizenship, not just for Dreamers, but for grandmas, people who have been working here on the farms, students who have overstayed their visas,” Warren said.

Bullock shot back: “That’s Obama’s homeland security secretary that said you’ll cause further problems at the border, not making it better.”

Hickenlooper, who has long antagonized Sen. Bernie Sanders (I-VT), started ripping apart his Medicare for All plan, one of the central parts of his agenda, which has ignited a new debate in the 2020 primary.

“You can’t just spring a plan on the world and expect it to succeed,” the former Colorado governor said, arguing that Sanders, who served as mayor of Burlington, Vermont for eight years, doesn’t have the governing experience to carry out ideas.

After a heated exchange, Ryan took his turn at jabbing Sanders over his signature policy.

“The only thing they have is possibly really good health care, and the Democratic message is going to be, ‘We’re going to go in and the only thing you have left, we’re going to take it and we’re going to do better.’ I do not think that’s a recipe for success for us,” Ryan said.