Presidential candidate and Ohio Gov. John Kasich again took aim at rival Donald Trump via Twitter on Sunday.

“Hate groups have no place in America,” Kasich said on Twitter. “We are stronger together. End of story.”

The tweet included a link to a Politico story, “Trump declines to condemn Ku Klux Klan.”

The story recounted a CNN interview with Trump in which the billionaire refused to disavow David Duke, a former grand wizard of the Ku Klux Klan, who has spoekn supportively about Trump.

While Trump had disavowed Duke before, and would again after the CNN piece, on the air he said, “I don’t know anything about what you’re even talking about with white supremacy or white supremacists, So I don’t know. I don’t know -- did he endorse me, or what’s going on? Because I know nothing about David Duke; I know nothing about white supremacists.”

He said he would have to do research before condemning Duke or the KKK.

But reports, including by CNN and Politico, noted that Trump had mentioned Duke in 2000 and identified him as a Klansman.

Kasich was not the only candidate to attack Trump over the interview. According to CNN, presidential contender Ted Cruz tweeted, “Really sad. @realDonaldTrump you’re better than this. We should all agree, racism is wrong, KKK is abhorrent.”