U.S. Senator Richard Blumenthal has opened a new inquiry into Tether, the issuer of USDT, the world's largest stablecoin and a core trading and settlement asset across crypto markets, seeking answers about reported payments the company made to a consulting firm co-founded by Bo Hines while Hines was still serving as a White House crypto adviser and helping shape federal stablecoin policy. It is the latest in a series of crypto-related investigations by the Connecticut Democrat, who has focused especially on Tether.

Blumenthal, the ranking Democrat on the Senate's Permanent Subcommittee on Investigations — a watchdog panel with broad authority to investigate fraud, waste and misconduct across government and business — sent letters on Thursday to Tether and to Nxum Group, the consulting company Hines started with his father and another partner. The letters to Tether CEO Paolo Ardoino and Nxum request details of the business arrangements between the two companies.

“The highly unusual terms and nature of Tether's business relationship with both Nxum and Bo Hines raise alarming ethical and legal concerns, indicating that Tether was likely well aware of the illegality and impropriety of issuing payments to a current White House official with such a direct role in shaping cryptocurrency legislation that was instrumental to its business,” Blumenthal wrote in the letter to Ardoino. Federal conflict-of-interest statutes generally bar executive branch employees from participating in matters in which they or their families hold a financial stake.

inquiry follows a report published last week by The Wall Street Journal that Nxum received large payments for consulting work for Tether while Hines was still advising President Donald Trump and his administration on crypto policy, including on stablecoin issuers significant to Tether. Hines' White House tenure overlapped with Washington's first major push to legislate on the sector: the GENIUS Act, the first federal regulatory framework for payment stablecoins, was signed into law in July 2025.

“Tether is aware of the allegations reported in The Wall Street Journal that form the basis of Senator Blumenthal's letter,” the company said in a statement. “External counsel previously conducted an in-depth internal investigation into the matter, which found no evidence of wrongdoing.”

Hines left the White House to take a job as Tether's top U.S. executive. CoinDesk was first to report earlier this year that Hines' company, which had little track record or experience in politics, was making millions of dollars as the main campaign-advertising provider for a political action committee associated with Tether.

Nxum has since hired Harry Jung, another official who previously worked as a White House crypto adviser. The White House office that advised Trump on crypto issues, meanwhile, has been left vacant following the departure of Patrick Witt, who had replaced Hines as its executive director.

Blumenthal has focused significant attention on the crypto industry, including Trump's memecoin, the crypto backers of the president's projects, the Trump family crypto firm World Liberty Financial, activities at Binance and, in particular, Tether. He issued a report on the stablecoin issuer's financial connections to Iran, and more recently demanded answers about Tether's relationship with its U.S. financial partner, Cantor Fitzgerald.

Ardoino criticized the senator's work this week, saying Blumenthal ignored important information and shared his report with the press before giving the company a look or a chance to respond.

Though Blumenthal's party has been in the Senate minority during Trump's time in office, the still-narrow odds of Democrats retaking the chamber have improved in recent weeks. Prediction market Kalshi currently gives them a 69% chance. If Blumenthal returns to chair the investigations subcommittee, it would grant him significantly greater powers to subpoena and control the agenda, and he has made clear that crypto would be high on his list of topic areas.

Original report: CoinDesk