Billionaire real estate mogul Donald Trump blasted President Barack Obama’s senior adviser Robert Gibbs Sunday as “vicious and hateful” after the former press secretary called Trump a “right-wing nut job” on Fox News.

“I was a great student at a great school, Wharton School of Finance,” Trump told Newsmax late Sunday night. “I built a net worth in excess of $8 billion, built a tremendous company and have employed tens of thousands of people. I hardly see where I qualify under his definition.”

“The Obama representatives like Robert Gibbs attack people viciously, but people like me will not be silent and will answer them back,” Trump said. “It is a shame that they are so vicious and hateful—and that is why the country is so terribly divided.

“Obama and his attack dogs have nothing but hate and anger in their hearts and spew it whenever possible,” Trump added. “Obama has no solutions. Obama has failed the country and its great citizens and they don’t like it when somebody such as myself speaks the truth about this—it hurts too much.”