The latest twist in Donald Trump's attritional war with US law enforcement, as with so much else in the former president's story, throws the United States into unprecedented territory.

Facing multiple federal charges over his hoarding of government secrets, the mercurial Republican presents the country with the possibility of a winning candidate moving into the White House while under indictment -- or running the government from a jail cell.

The defiant billionaire has dismissed the notion that he would ever drop out of his party's primary contest, reverting instead to a favored tactic of accusing his "corrupt" political adversaries of election interference.

"It likely won't sway undecided voters but it will galvanize Trump supporters who might be wavering or looking to a candidate with less baggage," Matt Shoemaker, a national security analyst and former intelligence officer, told AFP.

Prosecutors in both the federal documents case and the state-level financial fraud probe targeting Trump in New York will hope to have him face justice before the country goes to the polls in 17 months.

But there is no guarantee of either case wrapping up that quickly and Trump also faces federal and state-level probes into his efforts to subvert the 2020 election.

He would likely torpedo any outstanding federal prosecutions were he reelected, by attempting to pardon himself -- an unprecedented scenario that would almost certainly spark a constitutional crisis.

But he would have little influence over state-level cases and his more immediate worry is the damage his legal woes could do to his campaign to win the Republican nomination in the first place.

Going for the jugular?

The latest indictment allows Trump's primary challengers -- Florida Governor Ron DeSantis, former vice president Mike Pence and others -- to level the criticism that the runaway frontrunner is unfit for office.

But they run the risk of alienating Trump's loyal base, whose support has only grown more fervent since the Manhattan indictment.

As a result, many rivals have rallied to Trump's side, perhaps hoping to keep their powder dry until he is finally taken out of the running by further indictments expected in the coming months.

Trump is under federal investigation over his role in the January 6, 2021 US Capitol insurrection and media reports suggest racketeering and conspiracy charges are set to drop in Georgia in August over the tycoon's campaign to overturn the election there.

"They are hoping Trump is eventually knocked out of the race by a series of indictments, including those concerning January 6 and the attempt to overturn the election," said University of Virginia political scientist Larry Sabato.

"That's it. That's their strategy... They won't do anything. Go for the jugular? Trump's teeth will be in their jugular before they can do the same to him."

Prosecutors on Friday said Trump had been charged with almost 40 counts filed under multiple charges, including illegal retention of government secrets, obstruction of justice and conspiracy.

'Serious crime'

In a recent YouGov poll only half of respondents said it was a "serious crime" to falsify business records to conceal hush money payments to a porn star -- the case that he faces in Manhattan.

But two-thirds said the same about removing classified government secrets from the White House and obstructing efforts to retrieve them.

The figures are 28 percent and 42 percent respectively among Republicans -- a gap that suggests Trump's latest scandal could mark a turning point in his primary campaign.

DeSantis -- who has been polling a distant second to Trump -- has exercised restraint in comments over his rival's legal woes but the rhetorical hand grenades lobbed between the camps have become more bellicose in recent weeks.

Meanwhile Chris Christie, a political knife-fighter who has indicated he'll take on Trump more directly than the rest of the pack, has jumped into the race since the Manhattan indictment.

"DeSantis would most benefit from Trump dropping out of the race but he seems to have calculated that they have many of the same potential voters so doesn't want to alienate them," Shana Gadarian, a professor of political science at Syracuse University, told AFP.

"It may take someone like... Christie to shake up that narrative," she added. "Christie's candidacy is about bringing the mainstream back to the party and he may see the benefit of attracting former Republicans who were turned off by Trump's presidency."

© Agence France-Presse