MONACO (AP) — Red Bull boss Christian Horner expressed his surprise that Formula 1’s decision to block Andretti Cadillac’s attempt to join the series has reached the U.S. Congress.

This week, six U.S. senators asked the Department of Justice to examine whether F1’s decision to stop Andretti Cadillac becoming F1’s 11th team violated any antitrust laws.

“I was surprised to see that Andretti have gone down this process, but hopefully if they really want to find a way onto the grid they will find it,” team principal Horner said on Friday at the Monaco Grand Prix. “I think the most natural solution is for them to acquire an existing franchise should one want to sell.”

GM, under its Cadillac brand, is part of the Andretti Cadillac effort that has been denied by Formula One Management in its request to expand the F1 grid.

Although Michael Andretti’s bid was approved by motorsport governing body the FIA, FOM then rejected the application to join in 2025 or 2026 because it did not believe Andretti would be competitive.