Commerce Secretary Wilbur Ross is under fire due to unreported ties to Russia.

U.S. Secretary of Commerce Wilbur Ross, who has a key role in pushing for changes in the North American Free Trade Agreement, has come under new scrutiny due to unreported ties to Russia.

Ross, a highly successful investor, who became a billionaire by investing in distressed companies, including steel makers and automotive suppliers, has been one of the administration’s key players in the discussions with Mexico and Canada on changing NAFTA.

He has been expected to serve as a bridge between the auto industry, where he has well-established ties, and the Trump administration. 

The NAFTA talks, which are followed closely by the auto industry because of its huge investment in Mexico during the past two decades, stalled last month and are scheduled to resume in mid-November. Trump also raised the imbalance of trade with Japan when he met with Japanese leaders this weekend.

Despite a major backlash from business groups, including those representing auto makers, Trump has suggested he would like to cancel or withdraw from NAFTA and begin imposing tariffs on some goods made in Mexico, including cars and trucks.

Sen. Richard Bluenthal (D-Conn.) claimed that Ross misled him, the Senate and the American people.

Ross still controls a stake in a major automobile supplier, IAC or International Automobile Components, according to financial disclosure statements he filed with the U.S. Department of Commerce back in January as he appeared before the U.S. Senate Commerce Committee for his confirmation hearings.

However, new questions have been raised about whether Ross hid some key financial ties when he filled out the disclosure form earlier this year.

Sources familiar with his career in recent years have said Ross stepped aside from an active role in IAC in 2014 when he became involved with a stake in a Bank of Cyprus. At the time, Ross characterized his involvement with the bank as a turnaround opportunity similar to those he had pursued successfully in other industries.

However, Sen. Richard Blumenthal (D-Conn.) called for an investigation into Ross after it was revealed that Ross had failed to disclose shared business interests with members of Russia President Vladimir Putin’s family. The Bank of Cyprus has long been a favorite of Russian oligarchs, including several linked to Putin such as Oleg Deripaska, who was mentioned in connection with the federal indictment for money laundering by former Trump campaign manager Paul Manafort.

“Why do so many Trump associates have such trouble disclosing relationships with Russia?” Blumenthal tweeted Sunday about the new report.

“In concealing an ongoing financial relationship w/Russian oligarchs, Sec. Ross misled me, Senate Commerce Committee & the American people,” he tweeted. “Inexcusable and intolerable. Americans are owed answers on this Cabinet’s troubling failure to disclose links to Russian interests,” Blumenthal added.

“With Wilbur Ross revelations, question must be asked — whose interests come first in this Administration? Only after a thorough investigation can Americans be sure Secretary Ross really has their best interests at heart.”