Businessman who provided intel on Trump's alleged 'golden showers' was in email chains with Jared Kushner

Among the revelations from Congress' news blast claiming the president's aide and son-in-law Jared Kushner failed to provide documents about an alleged "Russian backdoor overture" is a smaller -- but still controversial -- contact he had with a Belarusian-American businessman.

Discussing the findings from a letter sent to Kushner's lawyers by the Senate Judiciary Committee, Business Insider's Natasha Bertrand told MSNBC host Chris Hayes that the lawmakers called the young real estate magnate out for failing to disclose that he'd been copied on emails from a businessman Sergei Millian.

Millian, who founded the Russia-America Chamber of Commerce trade group, has claimed to have a business relationship with Donald Trump. He is also the alleged source of the rumor that Trump once hired prostitutes in Moscow to urinate on a bed that gave the infamous Fusion GPS document the nickname "golden showers dossier."

Millian's name has appeared multiple times in 2017, most recently in relation to former Trump campaign aide George Papadopoulos. The reports from the Senate Judiciary Committee also claim that Millian was in regular contact with Papadopoulos after the latter tried to set up a meeting with him, Bertrand said.

The release of the committee's letter to the public, she continued, proves that Sen. Dianne Feinstein (D-CA), the ranking Democrat, and committee Chairman Chuck Grassley (R-IA) were "very frustrated."

"It was clearly an indication they are sick and tired of Jared Kushner omitting this very important information," Bertrand said, noting that it's rare for this committee to send letters so publicly.

Watch Bertrand explain the significance of Kushner's potential contacts with the controversial Belarusian-American below, via MSNBC.