"One of the reasons that I comfortably won the second time is (voters) saw that I worked very hard, paid attention to them, to Minnesotans, and paid attention to policy and did my work," Franken said in our Speakeasy interview at the Minnesota State Fair. "Donald Trump is the opposite.

He used his easy 2014 re-election, after the wafer-thin margin of his 2008 victory, to explain the difference.

"Wait a minute," he interjected in response to a question about common traits . "You lumped me in with Trump?"

Al Franken, the former "Saturday Night Live" star, current Minnesota senator and potential future presidential candidate, wants you to know how different he is from the former TV star now sitting in the Oval Office.

Senator Al Franken sits down with CNBC’s John Harwood at the Minnesota State Fair to talk politics and comedy on Aug. 31st, 2017.

"He doesn't work. He doesn't know how policy works. He won't do his homework. He refuses to

work on anything that matters," Franken said. "So I consider myself a polar opposite of him.

"And the fact that we are both in a branch of show business?" the second-term senator continued. "He was in reality TV. A human cannonball was in show business, you know? A rodeo clown's in show business."

As some Democrats urged him to consider a presidential bid, Franken says the controversies that hobbled him in 2008 have grown irrelevant. One of them — a late-night SNL joke-writing session that involved a fictional rape — pales next to the "Access Hollywood" tape that emerged last year in which Trump talked about his own conduct.

"I would be happy" to compare the two, Franken noted.

He also lambasted Trump as a president plagued by "temperament issues" who is "almost pathological in the way he lies." But without closing the door, he downplayed the possibility that he will challenge the incumbent.

"There's pretty much a zero chance, I think — I mean, unless, you know, I get hit in the head," Franken said. "I think that the president of the United States should be someone who really wants to be president of the United States.

"I've seen the job a little bit more up close as a senator than I did as a comedian," he concluded. "I can see what an incredibly high-pressured job it is. And it's not something that I've aspired to, ever."