Tim Walz is running for vice-president, but for a while on Wednesday night, it felt like he was campaigning to be the nation’s high school football coach.

Before he spoke, roughly a dozen of the players on the team he helped coach to a Minnesota state championship decades ago ran on stage, some wearing their old high-school jerseys, bouncing to the blasting horns of a marching band.

Once Mr Walz did appear, delegates in the packed arena waved signs that read “Coach Walz” – and the crowd chanted “coach, coach, coach!”

As this was Mr Walz's first significant opportunity to introduce himself to the nation, his speech was heavy on his personal story – his time as a football coach, of course, but also his upbringing, his enlistment in the Army National Guard, his work as a high-school teacher, and his service as a congressman and governor.

During parts of his speech his daughter Hope, 23, and son Gus, 17, were seen in tears in the front row of the arena. "That's my dad!" Gus mouthed as the television camera focused on him.

In the folksy style that the Democratic campaign believes connects with moderate voters in the crucial states of the Midwest, he told the crowd that he was "ready to turn the page on these guys", referring to Donald Trump and his running mate JD Vance.

"So say it with me: 'We are not going back.'"

He followed a diverse range of speakers and entertainers who took to the stage on the third night of the convention in Chicago, with Oprah Winfrey receiving the most raucous response after a surprise appearance in her hometown.

The four-day party extravaganza will culminate on Thursday evening when Vice-President Kamala Harris formally accepts the Democratic nomination, a little over a month after President Joe Biden stepped out of the race.

But on Wednesday night, everything built up to Tim Walz, a man virtually unknown to most Americans just weeks ago.

He drew from the first speech he gave in Philadelphia, Pennsylvania, earlier this month after being chosen as Kamala Harris's running mate, repurposing some of the same zingers.

“In Minnesota, we respect our neighbours and the personal choices they make,” he said. “And even if we wouldn’t make the same choices for ourselves, we’ve got a Golden Rule - mind your own damn business!”

Personal freedom has become a common refrain among Democrats at this convention and in pivoting to it, Mr Walz described "the hell of infertility".

IVF fertility treatment has become entangled in America's debate over abortion rights and the Minnesota governor has repeatedly alluded to the process on the campaign trail when talking about his family's story.

His wife, Gwen, recently clarified that they went through a different procedure, drawing Republican criticism that Mr Walz had been misleading.

On the convention stage, he said he wanted to talk about their struggle having children because this election was about "freedom".

“When we Democrats talk about freedom, we mean your freedom to make a better life for yourself and the people you love," he said.

“The freedom to make your own health care decisions. And, yeah, your kids’ freedom to go to school without worrying they’ll be shot dead in the halls.”

He also touted the Democratic priorities he has enacted while serving as Minnesota governor – including free school lunches, paid family and medical leave, middle-class tax cuts and lower prescription drug prices.

“While other states were banning books from their schools, we were banishing hunger from ours,” he said to cheers.

But it was the coaching theme he returned to again and again. When going on the attack against Donald Trump and JD Vance, he pointed to a frequent Democratic target – Project 2025, a think-tank policy blueprint designed in part by former Trump administration officials. The former president has disavowed its contents, but Mr Walz had a rejoinder.

“I coached high school football long enough, I promise you this - when somebody takes the time to draw up a playbook, they’re going to use it,” he said.

And in closing, he poured on the football metaphors, promising a pep-talk as the crowd again chanted “coach”.

“It’s the fourth quarter,” he said. “We’re down a field goal. But we’re on offence. We’re driving down the field. And, boy, do we have the right team to win this.”

Earlier in the evening, Ms Harris – if she were watching – had a chance to see a few of rumoured finalists in her vice-presidential selection process on stage.

Transportation Secretary Pete Buttigieg spoke of the positive effect government had opening the door way for him to start a family as a gay man. Pennsylvania Governor Josh Shapiro also hit on the personal freedom theme – focusing heavily on education, reproductive rights and fair elections.

“Kamala and Tim’s names may be on the ballot,” he said, “but it’s our rights and our freedoms on the line.”

Ms Harris opted for Mr Walz, however – and his particular talents were on display Wednesday night. He didn’t have Mr Shapiro’s soaring rhetoric or Mr Buttigieg’s eloquence, but Democrats hope his flat midwestern accent, his somewhat rotund physique and his thinning hair – combined with the small-town coach speak – will appeal to the kind of voters who have abandoned the Democratic Party when Trump is on the ballot.

Many Republicans said they were relieved at Mr Walz’s selection, as they feared the appeal Mr Shapiro would have in key battleground Pennsylvania.

And they’ve already been on the attack against the Minnesota governor – criticising what they view as too-liberal policies as governor and contending that he not only misrepresented the nature of his family's fertility treatments but also his rank in the Minnesota National Guard.

They haven’t yet found a way to dent his coaching record, however. And if Wednesday night in Chicago was any indication, that – as much as anything – is going to be a central focus of the Walz’s pitch to the public.