A bipartisan group of U.S. lawmakers have threatened to cut U.S. funding for the World Anti-Doping Agency (WADA), accusing it of failing to properly investigate alleged doping by 23 Chinese swimmers at the Tokyo 2021 Olympics.

The United States, which is the largest single country funder of WADA and which is also due to host the summer Games in Los Angeles in 2028 and the 2034 Winter Olympics in Salt Lake City, has accused the body of not disclosing that the swimmers tested positive for the performance enhancer trimetazidine (TMZ) months before the Tokyo Games.

The swimmers were cleared by a Chinese investigation, which said they were inadvertently exposed to the drug through contamination at a hotel where traces of TMZ were discovered in the kitchen. WADA said it had no evidence to challenge China’s findings.

The incident was not made public at the time, but some of the swimmers went on to win medals in Tokyo and are competing at the Paris Olympics.

The bill titled “Restoring Confidence in the World Anti-Doping Agency Act of 2024,” was introduced by Republican and Democratic lawmakers in the House of Representatives and the Senate and will give the White House Office of National Drug Control Policy (ONDCP) permanent authority to reduce or revoke U.S. funding for WADA.

The incident has cast a shadow over the Paris Olympics and sparked a row between the global and American anti-doping agencies.

WADA responded to U.S. allegations by saying it would take the U.S. Anti-Doping Agency (USADA) to the Independent Compliance Review Committee, a move that could jeopardize plans for the U.S. to host the 2028 and 2034 Olympics.

The IOC, which established WADA, has told the U.S. to fall in line and added an amendment in the host city contract for the 2034 Games in Salt Lake City that would allow it to terminate the deal “in cases where the supreme authority of WADA” is not respected.