Franken’s staff, as he tells it, has been his best ally in stifling his funny side, sternly responding “O.K., that’s for inside the car” to his quips, and nixing his hilariously offensive responses to constituent letters. (He once composed a 110th birthday note to Ruth Anderson of Marshall, Minn., that read simply, “You have a bright future.”) They ruthlessly edit out his efforts to “slip in The Funny during speeches,” as when he attempted to state, in a nuclear-disarmament speech, “A wise man once said, ‘Trust but verify.’ That man was quoting Ronald Reagan.” Franken’s press secretary once threatened to write her own campaign memoir, entitled “‘Oh, C’mon!’ Said Franken.”

Still, Franken’s clever asides can’t always salvage his stale recitations of liberal talking points, which seem likely to persuade precisely no one who isn’t already a member of the choir. (Even with jokes, is anyone buying this book because he wants to read a seven-page argument against media consolidation?) In the end, this is a book your liberal aunt will love and your Republican neighbor will never pick up, much less enjoy. It’s not as funny as the best humor books, including Franken’s — but it’s a whole lot funnier than your average political memoir.

There’s surprisingly little here about the current president; Franken presumably began writing the book when Donald Trump wasn’t expected to win the election. In one chapter, he notes that he, too, is a former entertainer who’s had tax issues and been accused of degrading comments about women — making the case, of course, that Trump’s example is far worse. Another chapter is devoted to a faintly pathetic attempt to convince progressives they shouldn’t lose hope and can still make a difference.

More interesting than Franken’s political points is his description of the value of humor as a force for bringing people together. He devotes a lot of space to his friendly relationships with Senate Republicans, from the cranky Kansan Pat Roberts to Lindsey Graham of South Carolina, “the funniest Republican in the Senate.” (Informed that Franken is taking a vacation in Puerto Rico, Graham deadpans, “Do two fund-raisers: one with the folks for statehood, one with the folks against statehood. They never talk to each other.”)

He’s found common ground with such staunch conservatives as David Vitter of Louisiana, considers the present attorney general, Jeff Sessions, a personal friend and once wrote a country song with the Utah senator Orrin Hatch. He’s made McConnell laugh out loud: “Try to imagine what that looks and sounds like! You can’t!” After years of railing against George W. Bush while he was in office, Franken even manages to share a laugh with the former president when they run into each other. Maybe, he implies, we’d all be better off if we could dial back the partisan outrage and learn to take a joke.

Being in the Senate, Franken admits, has softened his own partisanship, though not everyone is treated gently. “I like Ted Cruz more than most of my other colleagues like Ted Cruz,” Franken writes. “And I hate Ted Cruz.” In the chapter on Cruz, entitled “Sophistry,” Franken describes him as “an absolutely toxic co-worker,” “singularly dishonest” and a “sociopath.”

The publication of “Al Franken, Giant of the Senate” marks a major break with Franken’s previous political persona, one that is sure to stoke speculation about his future in a party that is desperately bereft of future prospects. Up to now, as Franken observes, his dogged unfunniness has been the default angle of every article about his political career, to wit: “No Joke: Franken Running for Senate.” The cliché has become so pervasive, Franken wryly notes, that when he dies, his obituary will surely be titled “No Joke: Former Three-Term Dead at 93.”

And yet it somehow never gets old: Just a couple of months ago, a column in National Journal was headlined “No Joke: Al Franken for President?” Now that would be hilarious.