Trump, who will moderate a GOP candidate debate on Dec. 28, says Romney struggles to stay in front, saying "I don't know what it is."
Trump tells NBC's "Today" accusations that Romney flip-flops on issues are absurd, saying "we all change our minds on things."
He brushed aside decisions by both Ron Paul and Jon Huntsman to stay out of the debate, calling them "joke candidates."
Trump says "a lot of Republicans, top Republicans, asked me to do the debate." And he also says that if he isn't satisfied the GOP is putting up a viable candidate against President Barack Obama, he'd again consider running himself.