“I’m not here to tell you some good jokes,” Bernie Sanders told the crowd in Underwood, Iowa. “I have a bad sense of humor. It wouldn’t work in any case.”

The Vermont senator was doing himself a disservice. He has some all right jokes.

Following Sanders around western Iowa the day he soared ahead of Hillary Clinton by 27 points in New Hampshire afforded plenty of opportunity to hear them. He held four events on Tuesday, and while his stump speech isn’t exactly a standup set, there were plenty of one-liners.

When Sanders announced he was running for president, as he told his audiences in Fort Dodge, Carroll, Underwood and Sioux City, political commentators immediately embraced the bid.

“The pundits said: ‘You comb your hair very nicely. You have a GQ look to you,’” said the 74-year-old politician, who is regularly unkempt. “What can I say? I’m stuck with this.”

It had been bitterly cold in Iowa, rarely raising above 14F (-10C). Sanders would begin his speeches with the gag: “Thanks for the Vermont weather.”

Not side-splitting, but such was the affection for Sanders that it seemed he couldn’t have drawn more laughter if he’d got down among the crowd and started tickling people with a feather duster.

He has also got a humorous aside about deciding to run for president. His wife finally allowed him to do it, he said: “She’s the sensible one.”

And after a lengthy rant about the excesses of Goldman Sachs – they helped “ruin the economy” and had to borrow $5bn from the government and no one was prosecuted, while an ordinary person could end up with a criminal record for stealing “dog food … or a tin of chicken soup” – there was usually a gag at Hillary Clinton’s expense.

“Without naming any names, Goldman Sachs also provides very, very generous speaking fees to some of the Democratic candidates,” Sanders said in Carroll, about an hour and a half north-west of Des Moines. He knew some of his rivals were good speakers, he said, but: “You gotta be really, really good to get $200,000 a speech.”

But like Sanders says, he is not here to tell good jokes. He talks mostly about the health of America. His diagnosis is grim.

Politicians are beholden to lobbyists and big business, he tells the crowds at his rallies. The healthcare system lags behind the rest of the developed world, he says. The tax system is designed to benefit billionaires instead of the middle class. One-tenth of 1% of the US population has as much wealth as the bottom 90%. There are more people in prisons than in any other country.

Despite all this, however, the mood at his rallies is usually upbeat. Someone is telling it like it is. Someone has a plan to fix things.

It helps that the attendees are often young, enthusiastic and optimistic.

David France, 19, was volunteering at Sanders’s first event of the day in Fort Dodge, an hour north-west of Des Moines. He was wearing a T-shirt covered in images of the candidate’s face. France recently lost his job at an Applebee’s restaurant, where he was a cook. He hoped to go to university, and eventual work in bio-diesel technology because he believes climate change is “serious factor”, but he couldn’t afford it, he said.

Sanders was a perfect match for France on the last two issues. The democratic socialist has been outspoken on climate change. And France liked that Sanders “wants to make community colleges free”. (He wants to make state universities free too.)

Sanders’s full-throated, physical performances also diffuse the humor. When he gets angry, which happens when he talks about billionaires, or banks, or lobbyists, or “the grotesque level of income inequality” in the US, he brings his mouth extra close the mic, causing distortion.

Anyone who has ever watched Sanders speak – or debate – on television will be familiar with his enthusiastic gestures. Sometimes he waves his finger in the air. Sometimes he swings his arms out above his shoulders, like an owl flapping its wings. Sometimes he thrusts his hands outwards from his chest as if thumbing invisible suspenders.

It pleases the crowd. As does the music; the Trammps’ Disco Inferno is played at each stop; the campaign having seized on the “Bern Baby Bern” internet meme. On Tuesday, David Bowie’s Starman played at the beginning and end of each rally. You’d be unlikely to hear that at a Mike Huckabee event.

After each event people flocked to Sanders, hoping to grab a selfie. At Fort Dodge, Meryl Hiler, from Rockwell City, a 25-mile drive west, was among the photo-hunters. She was brandishing her five-month-old daughter, Karys, towards the senator in a bid to improve her chances of a getting a picture.

Hiler failed to get her photo. But she left happy. “This is the closest Bernie’s come to home and I wanted to see him speak,” she said. Hiler said Sanders’s desire to “get rid of corruption in politics, get the big money out of political campaigns” had impressed her. She added: “He’s also just very approachable.”

Sanders enjoys huge popularity among young people, and true to form, baby Karys had also enjoyed his speech. “She took one nap,” Hiler said. “But otherwise she was engaged.”