Donald Trump Donald John TrumpHR McMaster says president's policy to withdraw troops from Afghanistan is 'unwise' Cast of 'Parks and Rec' reunite for virtual town hall to address Wisconsin voters Biden says Trump should step down over coronavirus response MORE lambasted Jeb Bush on Monday, describing his Republican presidential rival as "pathetic," "desperate" and an embarrassment to his own family.

"He doesn't even use his last name in his ads. He's a sad person who has gone absolutely crazy. I mean this guy, he's a nervous wreck. I've never seen anything like it," Trump told CNN's Wolf Blitzer during an interview Monday afternoon.

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"Jeb is having some kind of a breakdown," Trump continued. "He's an embarrassment to his family. He has to bring his mother out and walk his mother around at 90 years old. I think it's a very sad situation that's taking place."

Former first lady Barbara Bush recently joined her son on the campaign trail in New Hampshire ahead of the Tuesday primary there, and has criticized Trump in media appearances for his controversial remarks about women.

Trump's remarks came after a series of tweets from Jeb Bush earlier Monday targeting the outspoken real estate tycoon, calling him "a loser" as well as "a liar and a whiner" and going after him for questioning Sen. John McCain John Sidney McCainThe electoral reality that the media ignores Kelly's lead widens to 10 points in Arizona Senate race: poll COVID response shows a way forward on private gun sale checks MORE's (R-Ariz.) status as a war hero.

Trump fired back with a couple tweets of his own going after the former Florida governor over his support for Common Core education standards and arguing that Bush is "weak" on illegal immigration, attacks Trump reiterated on CNN.

It's not the first time Trump has called his rival a family failure, but his insults come as the Bush family rallies behind Jeb Bush. Both Barbara Bush and Jeb Bush's brother, former President George W. Bush, cut campaign ads for him.

Bush is ratcheting up his attacks on Trump heading into Tuesday's New Hampshire primary as he seeks to fins his footing in the GOP race. Trump remains atop the polls in the Granite State after taking second in the Iowa caucuses last week.