The House January 6 select committee’s final report into its investigation is expected to focus heavily on Donald Trump’s involvement in the Capitol attack and his potential culpability, opening a rift on the panel weeks before its scheduled release in the middle of December.

The nature of the final report – alongside criminal referrals to the justice department – is expected to be the defining legacy of the investigation that brought into sharp relief Trump’s efforts to stop the congressional certification of Joe Biden’s election win and return to the White House for a second term.

As the final report is currently drafted, an overwhelming focus is on the findings of the “gold team” that has been examining Trump and White House advisers’ roles in orchestrating a multi-part strategy to overturn the 2020 election, according to multiple sources familiar with the matter.

The move to home in on Trump, principally driven by the select committee’s vice-chair, Republican congresswoman Liz Cheney, was in part because the actions of the former president – which a federal judge has said probably violated several criminal statutes – were particularly compelling, multiple sources said.

But that fixation on Trump has exposed in recent weeks a deepening rift on the panel, with the since-departed lawyers on the other teams, including the “blue team” examining issues like intelligence failures by the FBI, angered that their findings were set to be relegated to appendices.

The simmering discontent from some of the current and former staff has since reached the panel’s members, and an NBC News story earlier this month has since prompted discussions about changing some of the eight chapters in the final report, though they were already broadly complete.

The members, one of the sources said, have discussed inserting some of the findings of the non-gold team investigators in the January 6 narrative. But the members have been reluctant to highlight conduct by Trump’s allies that might have been unsavory but probably not criminal.

The final report is still scheduled to be released in the middle of December, and after the Senate runoff election in Georgia, where the Trump-backed candidate Herschel Walker trailed the Democratic incumbent Raphael Warnock in the general election in a disappointing midterms for the GOP.

At the same time, the select committee is weighing what potential criminal and civil referrals to the justice department might involve; the panel was scheduled on Tuesday to receive a briefing from a special subcommittee led by congressman Jamie Raskin examining the matter.

The subcommittee, which also involves Cheney, Adam Schiff and Zoe Lofgren – members with a legal background, or, in the case of Schiff, prosecutorial experience – has also been tasked with resolving other outstanding issues including how to respond to Trump’s lawsuit against his subpoena.

A spokesman for the panel could not immediately be reached for comment.

The question of whether and what referrals to make to the justice department has hovered over the investigation for months since the select committee’s lawyers came to believe that Trump was involved in a criminal conspiracy to defraud the United States and obstruct Congress over January 6.

The select committee won a substantial victory in March when the US district court judge David Carter ruled that Trump “likely” committed multiple felonies in his efforts to overturn the results of the 2020 election and stop the congressional certification of Joe Biden’s election win.

But some members on the panel in recent months have questioned the need for referrals to the justice department, which has ramped up its investigation into the Capitol attack and issued subpoenas to Trump’s allies demanding appearances before at least two grand juries in Washington.

The attorney general, Merrick Garland, last week appointed Jack Smith to serve as special counsel overseeing the probe into whether Trump mishandled national security materials and obstructed justice, as well as key elements of the criminal inquiry into the Capitol attack.

And even before the appointment of Smith as special counsel, the department asked former vice-president Mike Pence whether he might voluntarily testify to a grand jury hearing evidence about efforts to stop the certification on January 6, the New York Times earlier reported.