Cruz paints him as ‘hard-left like Bernie Sanders’ but the challenger for the Senate seat is drawing crowds in conservative suburbs

The star arrived late, which only added to the frenzy when he finally emerged on stage to be hailed by a full house of screaming fans who were thrilled by a set of his best-loved hits.

Since Beto O’Rourke is a politician, and a relatively unknown Texas Democrat at that, this gig was far from politics as usual. And that sense of upending norms is perfectly on-brand for the 45-year-old in his underdog bid to eject Ted Cruz from the US Senate in November.

There was the location: a conservative suburb west of Houston. The crowd size: about 600 people in a private school’s auditorium and several hundred more watching on a screen in an overflow room. Afterwards a line snaked past classrooms and the dining hall to the main staircase as 200 people queued for a photo-op with O’Rourke.

And the message: stubbornly – and perhaps counterintuitively for these times – optimistic and inclusive. He called for an end to “smallness and meanness and paranoia and anxiety and hatred”, urging the state and the nation to slice through partisan rancour, “come together” and develop a more civil discourse.

Sign up to receive the top US stories every morning

A year on from Hurricane Harvey, O’Rourke suggested, perhaps Congress should be spending billions of dollars on a coastal barrier to protect south-east Texas from natural disasters rather than building a border wall to block Mexicans.

A one-time guitarist in a punk band, he clasped the fingers of one hand tightly around the microphone head while thrusting the other out every few seconds for emphasis, as if he were rapping rather than delivering a stump speech.

“There’s a lot of people who are really fed up with negativity and the thing that Beto does is he opens the door, he allows them to come in,” Sri Preston Kulkarni, a Democratic congressional candidate who introduced O’Rourke last Thursday, told the Guardian.

Facebook Twitter Pinterest Senator Ted Cruz, left, on the campaign trail in Temple, Texas, this month. Photograph: Will Weissert/AP

In elements of his platform and the temperature of the fan fever, O’Rourke’s campaign perhaps echoes Bernie Sanders’ tilt at the 2016 Democratic presidential nomination, which rapidly evolved from quixotic to credible. It’s a comparison that Cruz is happy to stress as he pursues a rather less conciliatory tone that is focused on cementing his base.

Two days before O’Rourke’s event, Cruz gave a lunchtime speech and Q&A session at a barbecue joint near Houston called Big Horn. About a hundred supporters chewed on brisket and choked on the idea that Texas might elect a man who, Cruz said, is “running hard, hard left like Bernie Sanders”.

To isolated gasps, Cruz also floated the idea that O’Rourke is even further left than Sanders or the Massachusetts senator and rumoured 2020 contender Elizabeth Warren: “If you want a big government, gun-grabbing liberal, well, the Democrats are giving you one,” Cruz said. “You cannot find a race in the country with a starker difference”.

O’Rourke is giving up a safe congressional seat in the border city of El Paso, where he was born, to run against the Republican incumbent. Of Irish-American heritage and fluent in Spanish, he graduated from Columbia University and worked in internet and software businesses before serving on El Paso’s city council.

An advocate of legalising marijuana, he was elected to the US House of Representatives in 2012, defeating an incumbent who formerly headed the border patrol in El Paso.

Facebook Twitter Pinterest Beto O’Rourke greets a supporter before a town hall meeting. Photograph: Chris Covatta/Getty Images

He supports immigration reform, universal healthcare, equal rights for LGBT people, tighter environmental regulations and “commonsense” gun laws. In short, the kind of policies that would be mainstream in some other states and many western countries, but which prompt rightwingers to depict him as a deranged socialist who wants to destroy the fabric of Texas.

“This is a volatile election,” Cruz told the audience. “The hard left are energised, they’re angry and they hate the president. They are going to show up in massive numbers in November’s election. Here’s the good news – there are a whole lot more conservatives than liberals in Texas.”

Of Texas’s six biggest cities, five voted for Hillary Clinton over Donald Trump in 2016 and most border counties are strongly Democratic. Overall, though, Trump won 227 of the state’s 254 counties – all of which O’Rourke has made a point of visiting during his campaign.

Cruz looked comfortable on his down-home turf, with deer heads mounted on the wall, and received a standing ovation as he arrived, declared “God Bless Texas” and launched into an anecdote about beating the California-based talkshow host Jimmy Kimmel at basketball. Indeed, the stop kicked off a run of four appearances at Texas barbecue restaurants in five days for Cruz. (He began the week at a comfort food establishment named the Dixie Grille.)

Still, despite pledging to eschew money from political action committees (Pacs) and rely on small individual donations, O’Rourke raised $10.4m in the second quarter of this year compared with Cruz’s $4.6m.

Facebook Twitter Pinterest Beto O’Rourke has drawn crowds across Texas’s 254 counties. Photograph: Chris Covatta/Getty Images

The 47-year-old reached the Senate by winning 57% of the vote as a Tea Party insurgent in 2012. Now, as one of the best-known politicians in the country after his 2016 presidential campaign, Cruz needs to turn out his mainly white, highly conservative and largely suburban and rural loyalists to overcome determined urban progressives and moderates who might flip or stay at home because of unease over the Republican party’s direction under Trump.

While one poll from June put Cruz only two points ahead, a RealClearPolitics average of polls gives Cruz a 6.5 point advantage.

“It’s a no-brainer. I think Beto is going down. This is Ted Cruz country and it’s constitutional country and it’s Texas,” said Suzette Griffin, a retiree in an “I love Ted Cruz” T-shirt from 2016. “He’s for everything we’re against. He wants to give away the farm. He wants socialism and we don’t,” she said. “I think Ted’ll take him by 10 or 12 points.”

Two days later, Carol Wheeler sounded optimistic as she surveyed the packed theatre. “Look at this – this is Katy, very Republican! So it’s very exciting. We’ve been working hard, knocking on doors, spreading the word that he’s a very positive person, strong values, people-oriented,” the O’Rourke supporter said, sporting a badge with the slogan “Resistance, Insistence and Persistence”.