- "I think he's nuts. He's the grandson of German immigrants. He ought to be ashamed of himself," he said
- "It's very divisive. It's not the kind of America I believe in and I don't think it's the kind of the America that most Americans believe in," Dukakis said
"I think he's nuts," the 1988 Democratic nominee told CNN's Wolf Blitzer. "He's the grandson of German immigrants. He ought to be ashamed of himself."
"I'm very proud of my background," said Dukakis, whose parents immigrated from Greece. "This is the guy who's the grandson of somebody who came over from Germany. And I don't know what he's talking about for one thing. It's preposterous."
The former Massachusetts governor -- whose failed presidential bid will be prominently featured in CNN's new episode of "Race for the White House" that airs Sunday at 9 p.m. ET -- also called Trump's plan to build a wall "ridiculous."
"It's very divisive. It's not the kind of America I believe in and I don't think it's the kind of the America that most Americans believe in," Dukakis said. "I hope at one point, he's going to start addressing real issues facing this country."
Dukakis, who has endorsed Hillary Clinton, added that he doesn't think Sanders should drop out of the race.
"I think if he wants to stay in, he should," Dukakis said. "And frankly, this is such an incredible opportunity for the Democratic Party. To have this kind of food fight on the other side and to be able to go to work and make this a 50-state campaign."
"We've got to organize this country. We've got to work with the people across this country," he added. "If we do so, we're not only going to win the presidency, we're going to win the Congress back."