House Democrats on Monday alleged President Donald Trump lied to former Special Counsel Robert Mueller about his knowledge of his 2016 campaign team’s communications with WikiLeaks.

Lawyers for Congress’s lower chamber stated their belief in a court filing as part of the House Judiciary Committee’s request for the redacted portions of Mueller’s report on Russian interference in the 2016 election. These grand-jury redactions have stayed undisclosed largely due to legal concerns and because the Justice Department has said it opposes their release.

“Not only could those materials demonstrate the president’s motives for obstructing the special counsel’s investigation, they also could reveal that Trump was aware of his campaign’s contacts with WikiLeaks,” the attorneys wrote in the court filing.

House of Representatives lawyers pointed to an excerpt from Mueller’s report concerning Paul Manafort‘s testimony to support their allegations against Trump. The attorneys noted that Manafort, Trump’s former campaign chairman, said he “recalled” the president repeatedly requested to be “updated” on WikiLeaks’ hacks of emails belonging to the Democratic National Committee. The legal team pointed to a redacted portion in that excerpt.

“The text redacted … and any underlying evidence to which it may point are critical to the committee’s investigation,” the lawyers wrote.

“Those materials therefore have direct bearing on whether the president was untruthful, and further obstructed the special counsel’s investigation, when in providing written responses to the special counsel’s questions he denied being aware of any communications between his campaign and WikiLeaks,” the legal team added.

In November, Mueller’s office revealed Manafort broke his plea deal with federal investigators by repeatedly lying about his multiple secret meetings with WikiLeaks founder Julian AssangeIt was also reported at the time that one of Manafort’s attorneys regularly met with Trump’s legal team to brief them about the inquiry into Russian interference in the 2016 election.

House lawyers also wrote in their filing that Mueller’s grand jury redactions could likely help Democrats’ investigation into Trump’s July 25 phone call with Ukraine’s president, in which he pressured the nation’s leader to investigate Joe Biden and his son. The controversy led House Democrats to announce a formal impeachment inquiry last week. The House Intelligence Committee is also probing whether Trump tried to push Ukraine to prosecute people who testified against Manafort, who famously lobbied for pro-Russia political entities in the country for years.

Trump mentioned Mueller in his phone call with Ukrainian President Volodymyr Zelensky and called the former special counsel “incompetent,” according to the transcript of the conversation.