Analysis by Stephen Collinson, CNN

(CNN) — The idea that any White House candidate would show up in court, just six days before the Iowa caucuses, to challenge a 250-year understanding of the scope of the presidency is extraordinary.

But Donald Trump will again try to stretch those powers to save himself on Tuesday in a high-stakes court gambit that, if it succeeds, would place him and anyone else elected president above the law.

Given the 45th president’s oft-stated belief that he had near omnipotent powers when he was in office – and that he still might be entitled to them – the history-making spectacle about to unfold is not that surprising. The front-runner for the GOP nomination says he will be in the US Court of Appeals for the District of Columbia Circuit to watch his lawyers argue that he has “absolute immunity” from prosecution in his federal 2020 election interference case.

The case, and a looming trial, springs from Trump’s efforts to thwart the will of voters after he lost the 2020 election to Joe Biden. But with its proximity to Monday’s Iowa caucuses, which kick off 2024 voting, the case represents an ominous foreshadowing of how Trump envisages a possible second term. The former commander in chief has already warned that a possible return to the White House would be dedicated to “retribution,” which would likely test constitutional constraints as never before.

Trump on Monday made similar immunity claims in Georgia, where he’s trying to dismiss the state-level criminal charges against him, which stem from his efforts to subvert the election in the swing state.

If he were able to establish in the courts, albeit in a long-shot case, that an ex-president is free from prosecution for alleged crimes he committed while in power, he could not only loosen the constitutional guardrails around the office if he wins in November. He could change the way presidents act in the future – and the extent to which any autocratic instincts can be held in check.

Trump has already given a sobering warning of how he would react if his appeal is denied and he ends up back in the White House.

“Of course I was entitled, as President of the United States and Commander in Chief, to Immunity. I wasn’t campaigning, the Election was long over. I was looking for voter fraud, and finding it, which is my obligation to do, and otherwise running running our Country,” Trump wrote on his Truth Social network on Monday. “If I don’t get Immunity, then Crooked Joe Biden doesn’t get Immunity,” Trump went on to write, saying, “Joe would be ripe for Indictment.”

Once again, as he looks to secure a big win in Iowa next week, Trump is trying to leverage his criminal peril to advance his campaign narrative that he’s being politically persecuted.

Trump’s made a career of amassing power

During a turbulent career in business, through his domineering showbiz persona in “The Apprentice” and throughout a tumultuous presidency, Trump delighted at being the most powerful person in the room. The twice-impeached, four-times-indicted ex-president often gives the impression that rules and laws that govern everyone else don’t apply to him. He has pleaded not guilty to all criminal charges against him.

His appeal to the three-judge appellate panel is expected to end up at the Supreme Court – which denied special counsel Jack Smith’s request to skip the appellate courts and fast-track the issue without comment or noted dissent. Many experts view Trump’s appeal as an attempt to delay his trial, which had been due to start in March, until after November’s election. But no one could deny it also fits Trump’s pattern of trying to bend power to his will.

He’s arguing that his attempts to overturn the 2020 election were consistent with his official duties as president, as stated in the Constitution, to ensure the laws are faithfully executed. But it’s a perversion of the office to suggest that seeking to disrupt the transfer of power falls somewhere within the duties of the president. There is no constitutional role for the president in counting votes or certifying election results.

Smith, who is leading the federal election investigation, warned in a filing to the appeals court that Trump’s position, if it is upheld, could open the way for future US leaders to wield power mendaciously, saying it “threatens to license Presidents to commit crimes to remain in office.” Under Trump’s interpretation of the law, the president would remain free from prosecution for such transgressions even after they are no longer in power.

Judge Tanya Chutkan, who will oversee Trump’s federal election trial if he loses his appeals and it goes ahead, might have been describing Trump’s entire vision of the presidency in rejecting his arguments in her lower court. She wrote that his “four-year service as Commander in Chief did not bestow on him the divine right of kings to evade the criminal accountability that governs his fellow citizen.”

This idea that Trump effectively was – and perhaps in the future could be – above the law has been rejected by several judges, since it appears to fly in the face of a fundamental American principle.

In another appeals court case in Washington, DC, Chief Judge Sri Srinivasan last month contradicted one of Trump’s bedrock beliefs that everything a president says or does in office is protected from liability.

The president “does not spend every minute of every day exercising official responsibilities,” read Srinivasan’s opinion as he ruled that the ex-president could be sued in civil courts over events surrounding his supporters’ attack on the US Capitol on January 6, 2021. “And when he acts outside the functions of his office, he does not continue to enjoy immunity. … When he acts in an unofficial, private capacity, he is subject to civil suits like any private citizen.”

‘Presidents are not kings’

The former president’s view of the unimpeded reach of presidential authority seems very much along the lines of former President Richard Nixon, who was forced to resign over the Watergate scandal in 1974. “Well, when the president does it … that means that it is not illegal,” Nixon said in his famed set of post-presidential interviews with David Frost.

While Trump was still president, another appeals court judge – Ketanji Brown Jackson, who has since been elevated to the Supreme Court by Biden – gave her view of his power grabbing when she ordered White House counsel Donald McGahn to testify before the House of Representatives over the Russia investigation. Jackson quoted founders James Madison and Alexander Hamilton and French diplomat Alexis de Tocqueville to explain the nature of the presidency.

“Stated simply, the primary takeaway from the past 250 years of recorded American history is that Presidents are not kings,” Jackson wrote.

Trump would beg to differ. He has often argued that presidents have absolute power and his four-year term was a constant exercise in pushing against the constraints that the courts, historical precedent and his own White House lawyers and staff tried to enforce. Trump, for instance, insisted that a phone call in which he appeared to use the prospect of military aid to coerce Ukrainian President Volodymyr Zelensky into announcing an investigation into Biden and his family was “perfect.” (He was impeached by the House for abuse of power over that issue but not convicted by the Senate.) He made similar arguments when evidence emerged of him pleading with Republican election officials in Georgia to “find” sufficient votes for him to overturn Biden’s election victory in the critical swing state.

Trump’s beliefs, and misunderstanding, of the job of the presidency were perhaps best summed up by his statement in July 2019 that the Constitution gave him untamed power. “I have an Article II, where I have to the right to do whatever I want as president,” he said. “But I don’t even talk about that.” Article II of the Constitution lays out the duties of the presidency — but it does not, in conventional interpretations, at least — suggest unfettered executive authority.

These arguments may be critical to resolving Trump’s deeply perilous legal issues. And as a constitutional matter, they could resonate for generations to come. But his status as the dominant figure in the GOP, his extreme rhetoric and his vows to wield strongman power — a key part of his appeal to his supporters — mean that they are also a vital and immediate political issue.

Trump is leaving no doubt that, if he returned to the White House, he would first wield presidential authority to try to end his criminal liability by having his federal cases ended. He’s also pledged to gut agencies like the FBI that he sees as an instrument of a “Deep State” that is out to get him.

Biden warned in a speech on Friday that Trump posed a grave threat to American democracy.

“Trump’s assault on democracy isn’t just part of his past. It’s what he’s promising for the future. He’s being straightforward. He’s not hiding the ball,” Biden said.