WASHINGTON (AP) — House Republicans are preparing to release a report on the findings of their investigation into former President Joe Biden and what they allege is potential misuse of the presidential autopen during his term.

The report, which is likely to be released in the coming weeks, centers on contested and thus far unsubstantiated claims that Biden not only visibly aged while in office, but that his mental state declined to a degree that allowed White House officials to enact policies without his knowledge.

"The House Oversight Committee has uncovered how the Biden Autopen Presidency ranks among the greatest scandals in U.S. history,” Oversight Committee Chairman James Comer, R-Ky., said in a statement. “As President Biden declined, his staff abused the autopen to carry out unauthorized executive actions. We have concluded interviews with key Biden aides and will soon report our findings to the American people."

The Republican-led committee declined to offer instances where investigators may have heard testimony or otherwise found instances when the autopen — a mechanical device that is used to replicate a person’s authentic signature — was abused. A spokesperson for the Republican majority on the committee said the cases would be detailed in the report but offered no further details.

The committee has interviewed more than a dozen former senior Biden administration officials as part of the investigation, pressing them for information on Biden's mental fitness while in office. Oversight Democrats have dismissed the investigation as a distraction and say the committee is turning a blind eye to wrongdoing by the Trump administration.

Biden has strenuously denied that he was unaware of his administration’s actions. He has also dismissed claims that he had mentally declined to a degree that inhibited his ability to lead as president while in office.

“Let me be clear: I made the decisions during my presidency. I made the decisions about the pardons, executive orders, legislation, and proclamations," Biden said in a statement over the summer. “Any suggestion that I didn’t is ridiculous and false.”

What the committee heard in testimony

Some Biden officials who were subpoenaed cited their Fifth Amendment rights and declined to answer questions, including Biden’s former physician, Dr. Kevin O’Connor; Anthony Bernal, former chief of staff to first lady Jill Biden; and Annie Tomasini, a former senior adviser to Biden. Other aides spoke to the committee.

Several aides admitted that the pace of Biden's schedule slowed over the course of his term, according to a person familiar with the private testimony who was granted anonymity to discuss it. Jeff Zients, who was chief of staff, said Biden’s decision-making slowed during the administration. Decisions that once required three meetings eventually required a fourth, he said.

Zients also discussed how to confirm the president's mental fitness to the public. Senior officials, including O'Connor, discussed whether Biden should undergo a cognitive exam, which O'Connor said he would take into consideration.

But even as they described signs of Biden's advancing age — he was 82 when he left office — some Biden officials also strongly pushed back on the central premise of the Republican investigation — namely that staff effectively usurped the powers of the presidency for themselves.

“There was no nefarious conspiracy of any kind among the president’s senior staff, and there was certainly no conspiracy to hide the president’s mental condition from the American people,” Steve Ricchetti, a longtime close adviser to Biden, told the committee.

Why the autopen questions matter

Biden's age, apparent frailty in office and meandering public speeches were central to President Donald Trump and congressional Republicans' messaging during last year's election cycle. The Trump White House has continued to mock Biden on the issue, going so far as to post an image of the presidential autopen in place of Biden's official portrait in a recently installed West Wing presidential portrait gallery.

But Republicans' fixation on the presidential autopen may have broader legal implications.

Trump and Republican lawmakers have argued that improper use of the autopen would raise the possibility that scores of Biden-era executive actions, pardons and laws may be ruled invalid in court. Trump has already ordered the Justice Department to investigate.

A Trump White House memo to Attorney General Pam Bondi argued that any cases where the autopen was used without Biden's knowledge would be an “unconstitutional wielding of the power of the presidency” that “would have implications for the legality and validity of numerous executive actions undertaken in Biden’s name.”

The argument is legally untested and may raise difficult questions for Trump's own use of the autopen. Republican lawmakers insist that the Biden White House example was an exceptional situation.

Republicans have also argued that any former staffers found to have misused the autopen should be criminally prosecuted.

Legal experts and Democrats have called the arguments preposterous and warned that such precedents would imperil many of Trump's own policies from both of his terms in office.