The National Collegiate Athletic Association says the state will forfeit 133 applications for events if it is not repealed in two days, reports say.
Under House Bill Two (HB2), transgender people must use toilets that correspond to the sex on their birth certificates.
The bill also removed several anti-discrimination measures.
North Carolina is under mounting pressure to repeal the bill, which has already led some businesses, entertainers and teams to boycott the state.
The NBA moved its high-revenue 2017 All Star game from Charlotte and the NCAA itself moved seven games from the state during the current season. The state stands to lose up to $3.8bn (Â£3bn) over 12 years as a result of the boycott, AP news agency says.
However state officials have failed to reach an agreement despite months of negotiations.
On Tuesday Republicans in the US Congress and North Carolina's Democratic governor blamed each other for the continuing impasse.
Republicans are believed to be pushing for a religious conscience provision as a compromise in the deal.
That would copy a bill enacted in Indiana allowing service providers to object to state law if they deem it contrary to their religion.
A US sports body says it will stop holding events in North Carolina if the state does not revoke its controversial "bathroom bill".