“If your bank is @jpmorgan you simply have to move your money elsewhere,” one fan posted on Twitter. “Say NO to the #SuperLeague.”

A theme of the ire from fans in Britain, in particular, was that the move represented another step in the foreign takeover of the game, especially by American interests. The Wall Street bank will lend to clubs controlled by American owners, like Arsenal, Liverpool and Manchester United — three of the six English clubs that are founding members of the proposed league.

The competition would largely do away with promotion and relegation based on performance, making it more like American sports leagues: With a U.S.-based bank in the background, it “smacks of the N.F.L. template,” said one British commentator.

That said, the prime mover behind the proposal isn’t an American but Florentino Pérez, the billionaire president of Real Madrid who has proposed a version of the Super League before, according to a person with knowledge of the matter who spoke on condition of anonymity. Mr. Pérez previously relied on JPMorgan to help finance a renovation of his club’s stadium.

The Super League’s backers have already filed motions in multiple courts to challenge any attempts to stop the project.

Other than its size, the actual financing of the league may not be overly complicated, because it is similar to debt raises arranged by American sports leagues, the person briefed on the matter said. The bank is probably betting that lending to a new competition featuring top soccer teams will prove lucrative — assuming it gets off the ground.