Trump sold the property in 2008 for $95 million to Russian oligarch Dmitry Rybolovlev, after purchasing it for $45 million four years earlier. Trump has attributed the flip to renovations he made on the property. At the time it was considered one of the most expensive house sales on record.

“It is imperative that Congress follow the money and conduct a thorough investigation into any potential money laundering or other illicit financial dealings between the president, his associates, and Russia,” Wyden, D-Ore., wrote in a letter to Steven Mnuchin, the treasury secretary.