On the night a dozen of Donald Trump’s Republican rivals spoke at the same event in Iowa, only one challenged the former president head on – and he was roundly booed. It highlights the grip Mr Trump still has on his party.

Someone backstage at the Lincoln Dinner clearly had a mischievous sense of humour.

As each of the candidates hoping to become the Republican Party’s presidential nominee for 2024 walked out to speak they were accompanied by a blast of music: a clip of the country song Only In America.

When it was Mr Trump’s turn, two lyrics, describing two alternative paths that could await someone in the US, seemed particularly poignant:

One could end up going to prison

One just might be president

The 45th President of the United States didn’t seem to mind. He doesn’t try to hide from the fact that he is already facing two criminal trials and may soon be indicted in two more cases. In fact, he wears these charges as a badge of pride.

Mr Trump insists he is being unfairly targeted for purely political reasons.

He told the crowd of 1,200 Republican supporters at this dinner in Iowa – a key state because it will hold the first election in the race for the nomination next January – that he would not have been prosecuted if he was not running for the White House again. And he would not have been prosecuted if he was not winning.

Using serious criminal charges as a mark of success takes chutzpah. But that is something Mr Trump has always had in spades. And it leaves his opponents deeply confused about how to respond.

Most simply chose to ignore Thursday evening’s news that Mr Trump had been charged with three more counts in the classified documents investigation. In fact, they declined to take the opportunity to challenge the clear frontrunner in the contest at all.

One of the lesser known contenders, Will Hurd, did take a shot. The former Texas Congressman and CIA officer claimed Donald Trump was not running to make America great again.

“Donald Trump is not running for president to represent the people that voted for him in 2016 or 2020. Donald Trump is running to stay out of prison.”

Loud boos and rattling cutlery nearly drowned out the rest of what he had to say, with one man shouting “go home”. It was clear he had lost the room.

Stacey Taiber, one of many Republican voters wearing Trump stickers, told me she did not believe any of the charges against Mr Trump. If the political establishment were “trying so hard to get him out of the way they must be terrified he will beat Joe Biden”, she said.

Her husband, Dan, said it was President Biden and his son Hunter who should be facing criminal trials. He and many others in the ballroom repeated unproven allegations about Hunter’s business dealings and claims of foreign influence (which the White House has dismissed but Republicans in Congress are investigating).

There was no fun to be had watching the different candidates interacting with each other at the dinner. They each had their own backstage suite which they popped out of to deliver their 10-minute speech. They actually didn’t have to see each other at all.

Maybe there will be more fireworks when the candidates come face to face at the first Republican debate on 23 August – although Mr Trump has suggested he might skip it because he is so far ahead in the polls.

Chris Sununu, the Republican governor of New Hampshire, is no fan of the former president but recently ruled himself out of running against him in 2024.

He told me that for the other candidates to compete with Mr Trump it is not about what they say – because there are not significant policy differences – it is about how they perform.

“They need to be exciting, bring some passion, show some emotion, and they need a bit of humour and charisma.”

Who voters like and who they think can win is what matters, he added, noting that it was very hard for newcomers to the national stage to compete with the name recognition and star power of a former president.

Vivek Ramaswamy, the millennial entrepreneur and political novice, was one candidate who showed at Friday’s dinner that he has the potential to break out from the crowded field of candidates currently polling in single digits.

After a barnstorming performance, he got one of the few standing ovations – along with Mr Trump and Florida Governor Ron DeSantis, the candidate currently sitting in second place in most surveys.

Outside the venue there was a stall selling the usual badges, T-shirts and baseball caps. Thirteen candidates appeared on stage (Chris Christie was the only official contender not to attend), but only four of them had their names on the merchandise.

Mr Trump, Mr DeSantis and Mr Ramaswamy, along with Tim Scott, the senator from South Carolina who has been getting a bit of attention recently.

“I’ve been making my living doing this for a long time,” the vendor told me. “I know what sells.” And Republicans have always been strong believers in market forces after all.