The House select committee investigating the Capitol attack will unveil new evidence at Watergate-style public hearings next week showing Donald Trump and top aides acted with corrupt intent to stop Joe Biden’s certification, according to sources close to the inquiry.

The panel intends to use the hearings as its principal method of revealing potential crimes by Trump as he sought to overturn the 2020 election results, the sources said, in what could be a treacherous legal and political moment for the former president.

As the justice department mounts parallel investigations into the Capitol attack, the select committee is hoping that the previously unseen evidence will leave an indelible mark on the American public about the extent to which Trump went in trying to return himself to the Oval Office.

“They’re important for setting a record for posterity, but they’re also important for jolting the American public into realizing what a direct threat we had coming from the highest levels of government to illegitimately install a president who lost,” Norman Ornstein, a political scientist and emeritus scholar at the conservative thinktank the American Enterprise Institute, said of the hearings.

The panel’s ambitions for the hearings are twofold, the sources said: presenting the basis for alleging Trump broke the law and placing the Capitol attack in a broader context of efforts to overturn the election, with the ex-president’s involvement as the central thread.At their heart, the hearings are about distilling thousands of communications between top Trump White House aides and operatives outside the administration and the Trump campaign into a compelling narrative of events about the events of 6 January, the sources said.

In order to tell that story, the sources said, the select committee intends to have its senior investigative counsels reveal previously secret White House records, photos and videos that will be presented, in real time, to starkly illustrate the live witness testimony.

On Thursday night, at the inaugural hearing at 8pm, the panel’s chairman Bennie Thompson and the vice chair Liz Cheney are likely to make opening arguments, outline a roadmap for the hearings, and give an overview of the events of 6 January, and the preceding weeks.

The panel is likely to focus on broad themes for the following four hearings, such as how Trump used false claims of voter fraud to undermine the 2020 election and future races, and how he tried to use fake electors to deceive Congress into returning him to office.

House investigators are also likely to focus on how Trump directly pivoted to the 6 January congressional certification – and not the December deadlines for states to certify their electors – as an inflection point, and how his actions led straight to militia and far-right groups’ covert maneuverings.

The panel is then likely to reserve its most explosive revelations for the final hearing in prime time, where select committee members Adam Kinzinger and Elaine Luria are expected to run through Trump’s actions and inactions as the 6 January attack unfolded.

The list of witnesses has not yet been finalised, the sources said, but it is expected to include top aides to former vice-president Mike Pence, aides to Trump’s former chief of staff Mark Meadows, and people with direct knowledge of militia group activities on 6 January.

From a legal perspective, the panel has already alleged in court filings that Trump and his external legal advisor, John Eastman, violated multiple federal laws to overturn the 2020 election outcome, including obstruction of Congress and defrauding the United States.

The select committee hopes that by revealing new evidence in hearings, the sources said, it can convince beyond a reasonable doubt the American public and potentially the justice department that the former president violated laws to reverse his 2020 election defeat.

Among the highlights of the already-public evidence include the revelation that Eastman, Trump’s external legal adviser, admitted to Pence’s counsel, Greg Jacob, that his scheme to obstruct Congress on 6 January was unlawful, but pressed ahead with it anyway.

The internal White House schedule for 6 January that the select committee obtained through the National Archives, meanwhile, showed that Trump would have known he had no plans to march with the crowd to the Capitol when he falsely promised that at the Ellipse rally.

House investigators are in many ways making their case to the American public, the sources said, since it is not certain whether the panel will make criminal referrals to federal prosecutors, given they’re not binding on the justice department, which has the sole authority to file charges.

But that quest will come with its own challenges, and the panel’s greatest difficulty is perhaps not so much whether they can show wrongdoing by Trump and his top advisers, but whether it can get Republican and independent voters to care.

The repeated delays in holding the hearings have meant House investigators were able to finish most of the evidence-gathering they intended to conduct (the committee initially anticipated holding them sometime in “the spring, then in April, then in May, and now in June).

Committee counsel recently told one witness who had been assisting the investigation for months that it didn’t expect to ask for any more assistance, according to two sources familiar with the inquiry. “We are pretty much done,” the counsel told that particular witness.

But the consequence of the decision to delay the start of public hearings, and the constant drip of news from the investigation, is that it might have driven some “6 January fatigue” – which Trump’s allies on Capitol Hill are intent on weaponising to defend Trump.

The former president’s most ardent defenders in Congress and top Republicans led by the House minority leader Kevin McCarthy are planning aggressive counter-programming to the public hearings that slam the panel as partisan, according to party aides.

The Republican National Committee has also circulated a one-page memo of talking points, Vox earlier reported, requesting that Trump surrogates attack the investigation as “rigged” – even though multiple federal courts have ruled the inquiry is fully legitimate.

Overcoming counter-programming to cut through to Republican and independent voters could pose a challenge, the panel’s members have privately discussed. After all, the sources said, the panel is not trying to convince Democrats of Trump’s role in the Capitol attack.

The prospect of collective public exhaustion over 6 January-related news, with each new revelation seemingly more shocking than the last, appears to have also pressed the select committee to cut its June hearings schedule from eight hearings to now six.

According to a draft schedule reviewed by the Guardian and first reported last week, the panel anticipates holding just the first and final hearings – on 9 June and 23 June – in prime time at 8pm. The other four – on the 13th, 15th, 16th and 21st – will be at 10am.

Still, the target audience for the select committee is not Republicans but swing voters, Ornstein said. “I don’t have any expectation that Republicans who believe the election was stolen will change their minds. But it’s about the other voters and whether it will jolt the Democratic base into understanding what the stakes are.”