Spirit Airlines said Monday it still supports Frontier Airlines’ $2.9 billion takeover bid for the airline, saying it was more likely to win regulatory approval than JetBlue’s competing $3.6 billion offer.

Spirit said antitrust regulators are unlikely to approve JetBlue’s offer because of JetBlue’s alliance with American Airlines in the Northeast, a deal that the Justice Department is suing to block.

“We struggle to understand how JetBlue can believe” that the Justice Department or a court would let JetBlue strike a deal with American, then buy Spirit, eliminating the nation’s largest low-cost airline, the Spirit board said in a letter to JetBlue directors. Read More from Press of Atlantic City.