"It’s not his thing. He doesn’t have the temperament for it," the New York real estate mogul told ABC News' George Stephanopoulos on "Good Morning America." "I think Ben just doesn’t have the experience."
Trump also blasted Marco Rubio, who’s emerging from the pack as an establishment alternative to Jeb Bush. “I’m not a fan. I think he’s overrated,” he said, adding that Russian President Vladimir Putin "would eat him alive.”
He also criticized Bush, saying he should “absolutely” drop out of the 2016 race. “He doesn’t have a chance," Trump said today.
Later this morning, Trump went after Bush again when asked to do a Jeb Bush impression. "I don’t like showing a person sleeping at a podium,” he quipped at a news conference for his new book.
He also jabbed Rubio over his personal finances, saying Rubio "certainly lives above his means - there’s no question about that."
When asked earlier on “GMA” about the controversy surrounding the Republican debates, Trump said he looked forward to answering the tough questions. “I just want to answer the questions and be done with it,” he said when asked about the backlash against debate organizers.
"We’re being asked very rude questions, many of them directed at me," he told Stephanopoulos. “I just want to have a debate. I want to answer tough questions."
Trump has said he will negotiate directly with debate hosts on formatting disagreements, despite a meeting Sunday night among 2016 campaigns aiming to collectively seek debate format information from networks.
A new NBC-Wall Street Journal poll out Monday showed retired neurosurgeon Carson grabbing the front-runner spot in the race for the Republican nomination, garnering 29 percent of Republican voters to Trump's 23 percent.
Trump also talked about his personal life during the interview, reflecting on his career and his family. "My work has always been all-encompassing," he said, but went on to say that he also prioritized his children.
"I think [my kids] would say I’ve been a really good father," he said. "I could be in the biggest deal, and if they call, I’m always there for them."
Trump also predicted Hillary Clinton will be the Democratic nominee, “unless she gets indicted.”
As for the Republican side, he said, “I think I will be the nominee.”