The House Intelligence Committee has sent letters to former chief Trump strategist Steve Bannon and President Trump's former campaign manager Corey Lewandowki inviting them to testify as the panel probes Russian election meddling and any ties to Trump associates, a source with knowledge has confirmed to CBS News. The committee has invited the two key former Trump aides to testify in the beginning of January, but the House does not reconvene for business in Washington, D.C., until Jan. 8.

The invitations don't necessarily mean both men will testify before the committee.

Lewandowski was interviewed by the Senate Intelligence Committee in October, as it also investigates Russian election meddling and any ties to the Trump campaign.

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Bannon was present in the White House for the first months of Mr. Trump's presidency, leaving this summer to return to Breitbart News.

Bannon and Lewandowski have both stayed visible since leaving the White House and the campaign, respectively. Bannon campaigned for Republican Roy Moore, who lost to Democrat Doug Jones in the Alabama Senate race. Lewandowski recently released a book he authored along with former Trump campaign aide David Bossie.

CBS News interviewed Lewandowski earlier this month about his book and time with the Trump campaign. When he was fired last year, Lewandowski said it felt like the worst thing that could happen, but later, he decided it could be the "greatest thing that ever happened," because he wasn't present for much of the controversy surrounding the Russia investigation.

"Maybe it was the greatest thing that ever happened because all of the things that took place basically took place after I left," Lewandowski said. "And if Bob Mueller or anybody else wants to talk, I'd be happy to because if anybody colluded or cooperated with Russia to impact the outcome of the election, I want that person to go to jail for the rest of their lives," Lewandowski said.

CBS News' Olivia Andrzejczak Gazis contributed to this report.