"I think that there should be hearings, and I'm certain there will be hearings in the Judiciary Committee on this matter," the Franken told CNN's Jake Tapper on "State of the Union."
His comments reflected the Democratic frustration with Comey telling lawmakers 11 days before the November 8 election that the FBI was reviewing new emails potentially connected to its investigation into whether Clinton mishandled classified information.
"Even more troubling is what we've heard from sort of the rogue elements of the FBI seemingly tipping off former (New York City) Mayor (Rudy) Giuliani that something was up. I mean, it just seems like -- that's not the FBI," Franken said.
"We will have hearings. I'm sure that FBI Director Comey will be before us," Franken said. "I think he should be able to answer questions about this, and he should be able to control the FBI."
Franken also defended the Clinton Foundation as Tapper pressed him on whether it should be shuttered if Clinton wins the election.
"I think that sometimes people should compare the two foundations, the Trump Foundation and the Clinton Foundation -- that the HIV drugs to millions of people vs. the Trump Foundation, which doesn't seem to have done much of anything for anybody other than Donald Trump," Franken said.
And he said he isn't worried about Minnesota -- where Trump is set to make a surprise visit to a state that hasn't voted for a Republican since 1972.
Asked if Clinton is in trouble there, Franken said, "I don't think so."
Overall, though, he admitted, "I'm always nervous."
"We run through the finish line," he said. "This is what I tell everybody, I go to canvassing centers, I say, 'Many of you have jobs, many of you have families -- ignore them. Get on the doors.' "