Martin O'Malley responds after Donald Trump calls him a 'disgusting, little, weak, pathetic baby'

Former Maryland Gov. Martin O'Malley (D)'s campaign said Friday it "speaks volumes" that real-estate magnate Donald Trump is the Republican Party's front-runner, after Trump called O'Malley a "disgusting, little, weak, pathetic baby" in an interview set to air over the weekend.

Trump directed the disparaging remarks at the Democratic presidential candidate in lieu of O'Malley's apology last month for saying, "All lives matter," after being interrupted by demonstrators during a conference.

"And then he apologized like a little baby, like a disgusting, little, weak, pathetic baby. And that's the problem with our country," Trump said during an interview with Jeanine Pirro aired on "Fox and Friends" Friday.

"How can you apologize when you say black lives matter, which is true. White lives matter, which is true. All lives [matter], which is true. And then they get angry because you said white and all … we don't want you to mention that. What's he need to apologize for?" Trump said, according to Politico.

In response, O'Malley's campaign said it was "not interested in engaging in a race to the bottom with Mr. Trump." Lis Smith, O'Malley's deputy campaign manager, pointed out that O'Malley had appeared earlier this week at Trump's hotel in Las Vegas with workers in an attempt to highlight their push to unionize.

"Governor O'Malley stands with those who have the guts to stand up to Donald Trump's hate speech," Smith told Business Insider. "It speaks volumes about the Republican Party today that this is their frontrunner. Unlike the rest of the Republican field, we're not interested in engaging in a race to the bottom with Mr. Trump."

The apology for which Trump attacked O'Malley came last month after protesters interrupted O'Malley's speech during the progressive Netroots Nation conference with chants of, "Black lives matter!"

He responded by saying, "Black lives matter. White lives matter. All lives matter," a response from multiple politicians that has led critics to charge they don't fully understand the purpose of the "Black Lives Matter" movement. Later in the day during an interview, O'Malley said he had made a "mistake" and "meant no disrespect."

O'Malley and Trump have sparred earlier in the presidential campaign, most notably over Trump's heated rhetoric on immigration. O'Malley told Business Insider last month that Trump's remarks about Mexican immigrants were "ugly," "hate-filled," and "racist."