After Pat Buchanan delivered an infamous speech at the 1992 Republican convention, couching the struggle with Democrats in terms of a “cultural war”, columnist Molly Ivins wrote that it “probably sounded better in the original German”. She did not live to cover a Donald Trump rally.

Ivins died of cancer in 2007, at the age of 62. Now, she is the subject of a documentary, Raise Hell: The Life & Times of Molly Ivins, which is making its way around the festival circuit after showing at Sundance and SXSW.

The film describes a remarkable life: born into Houston oil money, educated at Smith in Massachusetts, a hard-charging reporter too hard-charging for the New York Times, a champion of the people in Texas, a guardian of human rights with the American Civil Liberties Union, a syndicated columnist and bestselling author, a troubled soul, a brilliant wit who coined a withering nickname for former president George W Bush: Shrub.

Director Janice Engel does not mention Bush’s successor-but-one. But she does include shots of liberal dissent of today: the Women’s March, March for our Lives. This, she says, is because she did not want “he who shall not be named … anywhere near my film”.

“But I wanted specifically to show Molly’s amazing prescience. The things she wrote, 15, 20, 30 years ago are happening right now. Molly was a student of history. These things don’t go away and people don’t pay attention, but she certainly did.

“It’s amazing. I sometimes think she’s more relevant now than when she was delivering her message. Right now, across the world, democracy is in crisis.”

From her home in Austin, Ivins kept note of the Republicans’ hard-right turn, of the consequent Texification of US politics, on the machinations of those with power and the effects on those without it, on the beginnings of the great polarisation which has reached such depths today.

It all culminated with Bush’s assault on civil liberties in the name of dubious security, in the years after 9/11. Ivins’ final book, Bill of Wrongs, written like others with Lou DuBose, was a clarion call against suppression of protest and abuse of power that now might even seem quaint.

Engel chose her shots of protests against Trump, she says, to show “the passing of the torch”.

“People may say, ‘Who’s the next Molly Ivins?’ There. That’s the next Molly Ivins.

“There is nobody now who did what she did all in one person but there are a bunch of people who do. You have comedians who do what she does, you have Trevor Noah, Samantha Bee, Stephen Colbert, [but] they have a staff of writers who take the pieces they get from investigative reporters. And then you have the brilliant editors and columnists and pundits, and you have the hosts of their own shows, Chris Hayes and Rachel Maddow, people like that.

“Molly did all that they do separately and she did it two or three times a week. So when people say ‘Who’s the next Molly Ivins?’ I say it’s not one person, it’s a movement. It’s about passing the message on. I love the Women’s March in LA, that picture at the end of the film. If you look at it they’re all millennials, young people, they’re kids. The next generation.

“They’re inheriting this mess. I was very specific, to show that.”

‘Who’s getting screwed and who’s doing the screwing’

Ivins was young once, of course, an ambitious reporter in a world wreathed in smoke and misogyny. In Raise Hell, friends and family tell of her struggles and successes, her mentors and comrades, those in power she shook and even her dog named Shit. The end is desperately sad but much of the rest is very funny indeed.

For fundraising, Engel says, she came up with a tagline: “How many documentaries make you laugh?”

“And it’s true! There’s a lot of depressing shit out there but you’ve got to laugh. Molly said it, ‘You’ve got to have fun while you’re fighting for freedom. It might be the only fun you ever have.’”

Ivins’ greatest hits are many. Of one Texas lawmaker: “If his IQ were any lower, they’d have to water him twice a day.” Of Vice-President Dan Quayle: “If you put that man’s brain in a bumblebee, it would fly backwards.” Of Bill Clinton, the withering assessment that he was “weaker than bus station chilli”.

But she had a serious message. As Engel says: “If we don’t find a way to agree to disagree, if we don’t find a way back to dialogue, we’re in trouble. Laughter is the great unifier: it gets us to drop our defences, our reactions, our rage. We need to realise we have much in common with those who disagree with us, you know?

“As Molly said, ‘I don’t care about who’s screwing whom, it’s about who’s getting screwed and who’s doing the screwing.’ It’s really about the destruction of the middle class over these last 30 years or however long, and, as Robert Reich has said, if you destroy the middle class you destroy the democracy.

“Again, Molly said it: ‘It’s not a left-against-right issue, it’s a top-versus-bottom issue.’ It always has been. It’s about the haves and have-nots.”

Ivins may be in danger of being forgotten. For this piece, an unscientific trawl through the Strand bookstore in New York City turned up a sole copy of Bill of Wrongs, under “Americana”.

Engel, then, has a mission. Her film played at Sundance and SXSW and will tour festivals in the US and abroad, seeking an audience which may be found via streaming. Its message, the director says, comes from its subject. If the rights of the people are threatened, it’s up to the people to act.

In her final column, from which Engel took her title, Ivins put it this way: “Raise hell. Think of something to make the ridiculous look ridiculous.”

Engel simplifies it further: “VOTE.”

• Raise Hell: The Life & Times of Molly Ivins is available now on DVD and Digital