CHARLESTON, S.C. (AP) — Democratic White House hopefuls are seizing on President Donald Trump’s delayed response to the coronavirus outbreak, calling it the latest evidence of his incompetence and warning that the crisis may only deepen as a result.

But some experts and Democrats warn that the candidates risk exacerbating a public health crisis if they go too far in politicizing the virus that causes the COVID-19 illness.

Former Vice President Joe Biden, former New York Mayor Mike Bloomberg, Massachusetts Sen. Elizabeth Warren and Minnesota Sen. Amy Klobuchar all went after Trump during their CNN town halls Wednesday night. A number of the candidates have released their own pandemic policies, and Bloomberg is even airing an ad contrasting Trump’s response to the outbreak to his own handling of the aftermath of 9/11.

It’s a potent political issue, as it gets at what Democrats see as two major potential weaknesses for Trump: questions about his competence as president and health care issues.

“The threat from coronavirus and the chaos of the administration is front and center in everyone’s mind,” said Jesse Ferguson, a longtime Democratic strategist and former spokesman for Hillary Clinton’s campaign. “Not talking about it means you’re missing voters who are deeply worried about the public health threat and deeply concerned about the Trump administration’s incompetence.”

Warren, Klobuchar and Bloomberg have all released public health plans detailing how they’d address and prevent similar outbreaks as president.

During their CNN town halls, Warren warned that the economic impact of the new coronavirus could get worse. She and Klobuchar slammed Trump’s decision to put Vice President Mike Pence in charge of the coronavirus response, noting his controversial handling of an HIV outbreak in Indiana when he was governor.

And Biden has previously slammed Trump for “hysterical xenophobia and fearmongering” rather than respecting science on the issue.

But sounding the alarm on the administration’s coronavirus response also holds risks. Florida Rep. Donna Shalala, who served as secretary of health and human services under President Bill Clinton in the 1990s, had a stark warning for Democrats.

“Don’t open your mouth until you know what you’re talking about. This is politics. They need to listen to the scientists as well,” she said.

That is a major criticism Democrats have lobbed at Trump — that he has botched his response and fostered more confusion by publicly contradicting the scientists in his administration about the severity of the virus.

On Wednesday, the president sought to minimize fears at a White House press conference where he insisted the U.S. is “very, very ready” for an outbreak and predicted: “This will end…there’s no reason to be panicked.” But standing next to him, the health officials in charge of handling the outbreak predicted more cases are coming in the U.S.

Democrats are not immune to the critique themselves, however. During Tuesday night’s primary debate, both Biden and Bloomberg made the erroneous claim that Trump cut funding for the Centers for Disease Control and Prevention. While Trump proposed cuts to the CDC in his budget blueprint, he was overruled by Congress, and the eventual budget he signed included an increase in funding.