With Donald Trump listening intently in the courtroom, federal appeals court judges in Washington expressed deep skepticism Tuesday that the former president was immune from prosecution on charges that he plotted to overturn the results of the 2020 election.

The panel of three judges, two of whom were appointed by President Joe Biden, also questioned whether they had jurisdiction to consider the appeal at this point in the case, raising the prospect that Trump’s appeal could be dispensed with on more procedural grounds.

During lengthy arguments, the judges repeatedly pressed Trump’s lawyer to defend claims that Trump was shielded from criminal charges for acts that he says fell within his official duties as president. That argument was rejected last month by the lower-court judge overseeing the case against Trump, and the appeals judges suggested through their questions that they, too, were dubious that the Founding Fathers envisioned absolute immunity for presidents after they leave office.

“I think it’s paradoxical to say that his constitutional duty to take care that the laws be faithfully executed allows him to violate criminal law,” said Judge Karen LeCraft Henderson, an appointee of former President George H.W. Bush.

The outcome could carry enormous ramifications both for the landmark criminal case against Trump and for the broader, and legally untested, question of whether an ex-president can be prosecuted for actions taken in the White House. It will also likely set the stage for further appeals before the U.S. Supreme Court, which last month declined a request to weigh in but could still get involved later.

A swift decision is crucial for special counsel Jack Smith and his team, who are eager to get the case — now paused pending the appeal — to trial before the November election. But Trump’s lawyers, in addition to seeking to get the case dismissed, are hoping to benefit from a protracted appeals process that could delay the trial well past its scheduled March 4 start date, including until potentially after the election.

Underscoring the importance to both sides, Trump, the 2024 Republican presidential primary front-runner, attended Tuesday’s arguments even though the Iowa caucuses are just one week away and despite the fact that there’s no requirement that defendants appear in person for such proceedings. Making his first court appearance in Washington since his arraignment in August, Trump sat at the defense table, watching closely and occasionally taking notes and speaking with his lawyers.

His appearance and his comments afterward underscored his broader effort to portray himself as the victim of a justice system he claims is politicized. Though there’s no evidence Biden has had any influence on the case, Trump’s argument could resonate with Republican voters in Iowa as they prepare to launch the presidential nomination process.

After the hearing, Trump spoke to reporters at The Waldorf-Astoria hotel, which used to be the Trump International Hotel, calling Tuesday “a very momentous day.” He insisted he did nothing wrong and claimed he was being prosecuted for political reasons.

“A president has to have immunity,” he said.

Former presidents enjoy broad immunity from lawsuits for actions taken as part of their official White House duties. But because no former president before Trump has ever been indicted, courts have never before addressed whether that protection extends to criminal prosecution.

Trump’s lawyers insist that it does, arguing that courts have no authority to scrutinize a president’s official acts and that the prosecution of their client represents a dramatic departure from more than two centuries of American history that would open the door to future politically motivated cases.