Donald Trump's mounting legal troubles have not dented his status as the clear frontrunner for the Republican presidential nomination in 2024. In fact, the criminal charges have strengthened his position. Why?

The former US president has been indicted three times in the past four months - once in New York for alleged financial crimes, once in a federal court on charges that he mishandled sensitive government documents and obstructed an investigation, and on Tuesday, he was indicted in a federal court on charges he conspired to overturn the results of the 2020 election.

He is also facing a fourth possible indictment in Georgia for pressuring state officials to reverse his 2020 defeat there.

Through this all, Mr Trump's campaign has not just continued unabated, it has thrived.

An average of opinion polls from 31 July suggests he has a commanding lead of 37 points over his nearest rival, Florida Governor Ron DeSantis.

No-one else in the crowded field of 14 candidates scores over 6%, and more than half of them are not even at 1%.

Back in mid-February, Mr Trump's lead over Mr DeSantis in the average of polls was just two points (41% to 39%). That turned out to be the Florida governor's high point so far, however. While his star has faded and his poll numbers have plummeted, Mr Trump's support has remained rock solid.

And since the first indictment was brought in the first week of April - making Mr Trump the first former US president to face criminal charges - it has actually grown.

According to the average of polls, Mr Trump has been the first choice of a majority of Republican voters ever since that first arrest and court appearance.

According to Clifford Young, president of US public affairs with Ipsos, the bond between Donald Trump and his supporters - which equates to about 40% to 45% of the Republican electorate - will be difficult to break.

"They see the world through his eyes," he says. "His base believes he's been wronged. They believe that the indictments are politically motivated."

After Mr Trump's indictment for illegally retaining classified documents, the BBC spoke with a panel of Republican voters about their views on the former president - and found similar sentiments.

"This is so obviously a blatant attempt to take Mr Trump out of the presidential running," 61-year-old Trump-supporting Rom Solene of Arizona said. "And it is a sad day for our nation, considering that others, including Mr Biden, have been caught with classified documents in their possession."

Even Republicans like Luke Gordon, who doesn't support Mr Trump's attempt to recapture the White House, viewed the indictment with some scepticism.

"I don't doubt the legitimacy of the claims in the indictment, and I do not defend Trump's actions," the 21-year-old New Yorker said. "However, the motivation behind his prosecution and investigation remains of grave concern."

A June poll by CBS News, the BBC's partner in the US, illustrates the point

"We're really dealing with the tale of two Americas and two distinct bubbles," says Mr Young. "There's one bubble that sees Trump's behaviour as lawless. And there's another bubble that sees him as their champion - and that he's being attacked because of that."

Given this dynamic, there is little evidence that the third indictment or even a fourth will measurably alter the landscape of the Republican presidential race.

Indicting Mr Trump for challenging the 2020 election results may not resonate with Republicans, considering 84% shared the view that Joe Biden did not "legitimately" win the 2020 election, according to a March CNN survey.

That is a serious problem for his Republican rivals who are left to fight it out for the roughly 60% of the Republican electorate who tell pollsters they could be persuaded to back another candidate or would never support Mr Trump.

Most have been reluctant to criticise the former president over the criminal charges, conscious that it would upset his base, but have also struggled to make the case for why voters should pick them instead.

If Mr Trump's indictments haven't moved the political needle, next year's big question could be whether trials and possible convictions could finally alter the sharp partisan divides in US public opinion on Mr Trump.

Throughout the first half of 2024, Mr Trump will have to deal with a clash between campaign events and court appearances at his trials which could each last weeks.

He said on Friday that he would not end his presidential campaign even if he were found guilty and sentenced.

That's uncharted territory in US politics, but Mr Young says the key "leading indicators" to watch will be whether Mr Trump's favourability standing in polls and his "electability" - the view as to whether he can win back the White House - take noticeable shifts.

If that's the case, it could presage an erosion of his support in a way that the string of indictments, as well as all the other controversies over his eight years in the public sphere, have not.

For the moment, however, early head-to-head polls suggest Mr Trump is within striking distance of the current president. A recent Economist-YouGov poll had Joe Biden ahead of Mr Trump 44% to 40%. Morning Consult had the Democrat ahead by 2 points, 43% to 41%. Both leads are within the margin of error.

That suggests that familiar partisan battle lines are already being drawn - and that the 2024 election, like the two previous contests involving Mr Trump - will be narrowly decided.