On Thursday, the US justice department is expected to release a redacted version of special counsel Robert Mueller’s long-awaited report on Russian election tampering and the Donald Trump campaign to the public. The attorney general, William Barr, has announced a press conference at the justice department at 9.30am to discuss it.

Barr has previously described the Mueller report as having two parts: one part devoted to describing the Russian tampering efforts, believed to include a rundown of Russian contacts with Trump campaign officials; and one part devoted to evidence of alleged obstruction of justice by the president.

Here are five things to look out for with the release of the report, which reportedly runs to nearly 400 pages and is officially titled Report on the Investigation Into Russian Interference in the 2016 Presidential Election:

Obstruction of justice

The Mueller report “catalogu[es] the President’s actions” that could amount to an obstruction of justice by Trump, according to an earlier letter issued by Barr summarizing his view of the report’s findings. How much of this catalogue will the public get to see on Thursday?

Mueller left the decision of whether to charge Trump to Barr, who decided not to. But it appears that Mueller gathered substantial evidence of potential obstruction of justice by the president. In his letter, Barr quoted this line from the report: “While this report does not conclude that the President committed a crime, it also does not exonerate him.”

What did Mueller, a lifelong prosecutor, see or discover that led him to believe that the president might have committed a crime?

Contacts with Russia

According to Barr, the Mueller report does exonerate the Trump campaign from allegations that it conspired with Russia. In his letter, Barr quoted the report: “[T]he investigation did not establish that members of the Trump campaign conspired or coordinated with the Russian government in its election interference activities.”

But there are signs that the report contains new information about contacts between Trump campaign officials and Russian operatives. One source close to Mueller’s team told NBC News that the report “paint[s] a picture of a campaign whose members were manipulated by a sophisticated Russian intelligence operation”.

Trump’s political base appears to be unbothered by his campaign’s contacts with Russia, and by his subsequent chronic lying about those contacts. But could the report put those contacts in a new light?

Redactions

Mueller delivered his report one month ago, on 22 March. Since then, Barr and colleagues in the justice department have been preparing it for release to Congress and the public.

A big question is how much of the report will be redacted. Barr is seen as a Trump loyalist with a low opinion of Mueller’s investigation. Barr will probably be challenged to explain why certain material was deemed unfit for public view. Democrats in the House have already said they will subpoena the full report.

Barr has described to Congress four categories of material he intended to redact and said the redactions would be color-coded by category: first, grand jury information, including witness interviews; second, classified information; third, information related to continuing investigations; fourth, so-called derogatory information – information about people who were interviewed or scrutinized in investigations but not charged.

That last category could prominently include Trump.

Summaries

In the report, Mueller’s team included multiple summary paragraphs intended for quick public release after the report was submitted to Barr, according to multiple media accounts. Some members of Mueller’s team were reported to have been displeased that Barr did not release the summaries.

The report was prepared “so that the front matter from each section could have been released immediately – or very quickly”, one official not on Mueller’s team told the Washington Post. “It was done in a way that minimum redactions, if any, would have been necessary, and the work would have spoken for itself.”

Will we see the summaries? Will they be significantly redacted?

Scenes

Based on media reports and previous indictments, the public knows some of what was going on behind the scenes as the Trump campaign lurched toward victory in 2016, Russian operatives dangling off it, leech-like, on all sides.

But the Mueller report, which would draw on material not available to journalists, such as surveilled communications and seized evidence, could reveal what was really happening in some of the set pieces from the Trump campaign and early presidency.

We might find out more about what happened at a June 2016 Trump Tower meeting, and whether Trump was ignorant of the meeting, as he claims. New evidence could come to light about the firing of former FBI director James Comey. We could learn more about Trump campaign contacts with WikiLeaks.

The report could contain damaging new information about the conduct of Trump family members, including Donald Trump Jr and Jared Kushner, who have been accused of using the campaign to try to enrich their companies and keeping up inappropriate, if not illegal, contacts with foreign operatives.

The Mueller report might weigh in on whether Trump told Michael Cohen to lie to Congress, as Cohen has alleged, or whether Trump tried at least twice to fire Mueller, only to be stopped by the former White House counsel Don McGahn, as has been reported.

But key sections of the Mueller report might remain redacted for now.