George Papadopoulos told associates he was trying to strike a lucrative business deal with Russians after President Trump won the White House in November 2016, according to a letter sent to a Democratic lawmaker.

The former Trump campaign adviser, who is serving two weeks in federal prison after pleading guilty to making false statements to prosecutors as part of special counsel Robert Mueller's investigation, said the deal "would result in large financial gains for himself and Mr. Trump,” the Atlantic reported Wednesday, citing the letter. The uncorroborated claims are now under federal investigation.

The letter, sent last week to the likely new House Intelligence Committee Chairman Adam Schiff, D-Calif., was sent by a person who says they were close to Papadopoulos in 2016 and 2017. The panel and the FBI are examining the letter, according to the Atlantic. Papadopoulos' lawyer declined to comment to the outlet.

The statement also asserts that the ex-foreign policy adviser and Trump spoke via phone in December 2016, well after the campaign's conclusion.

Papadopoulos reported to the medium-security federal prison in Oxford, Wis., last Monday for his short stint.

In the early stages of Mueller’s probe, Papadopoulos lied about his contact with Joseph Mifsud, a Russia-connected professor who told him that Russians had dirt on 2016 Democratic nominee Hillary Clinton, when he was part of the Trump campaign, as well as a woman who claimed to be Russian President Vladimir Putin's niece.