Lawmakers could probe President Trump's son-in-law and close adviser Jared Kushner on whether he was attempting to sell a 41-story building in New York City to someone in Moscow, according to a report.

Kushner's family owns the tower, located at 666 Fifth Ave, and two congressional sources told NBC News that lawmakers want to know if Kushner proposed a secret communications channel with the Russians so he could find a buyer for the property in Russia. The questions could come if and when he testifies before Congress as part of the investigation into Russia's meddling in the 2016 election.

Kushner reportedly talked with Russian Ambassador Sergei Kislyak in December about setting up a backchannel between the Trump transition team and Russian officials in Russian diplomatic facilities.

National security adviser H.R. McMaster said last month he's "not concerned" about Kushner's attempts to establish a secret communications channel.

But that discussion, as well as a meeting Kushner had with Russian banker Sergei Gorkov, is likely to come up during congressional hearings.

No date has been set for Kushner to testify before the House and Senate Intelligence Committees, but Kushner's lawyer has said he's willing to answer questions about his contacts with Russian officials.

Kushner and his family real estate firm, Kushner Companies, purchased the building on Fifth Avenue in 2007 for $1.8 billion.

However, the company has not been able to make money off the property, according to the New York Times.

The firm was reportedly in discussions with Anbang Insurance Group, a Chinese firm, about investing $4 billion into the property when Kushner's contacts with the Russians occurred.

However, the Chinese firm pushed back on reports about their interest in 666 Fifth Ave.