Martin O’Malley says he’s not going to stop punching back against the “racist language” of Donald Trump—in part because he says the Republican’s rhetoric is the kind that has historically led to fascism.

O’Malley, the former governor of Maryland and a Democratic presidential candidate, told Fusion’s Jorge Ramos on Thursday that democracies can be “very susceptible” to scapegoating and racism.

“Especially after an attack or in times of economic downturn or stagnant wages,” he said. “And that’s where we are right now. So when Donald Trump says these things, all of us have an obligation to punch back. I’m certainly going to do it.”

Trump has drawn condemnation for his remarks on immigrants, Muslims, and Syrian refugees, among others. At the last Democratic debate, O’Malley called him an “immigrant-bashing carnival barker.” Trump has called O’Malley a failed mayor and a clown.

In the Fusion interview, O’Malley drew a dark historical parallel.

“These are the sort of appeals that history has taught us often times precede fascism,” he said. “Or worse, or just as bad, the plunging of a republic into a security state. We all need to push back on Donald Trump’s hateful language and racist language.”