Spirit Airlines rejected Frontier Group's acquisition offer worth about $2.16 billion, marking the latest failed deal in the years since the companies began discussing a merger.

After filing for bankruptcy protection and going back and forth with Frontier Airlines — again — over a potential acquisition, Spirit Airlines has a new plan.

Spirit Airlines Tuesday rejected Frontier's most recent merger proposal, opting to proceed with its own standalone recapitalization without a merger instead. Spirit is currently in bankruptcy.

Spirit Airlines is rebuffing the latest takeover offer from Frontier Group, with the discount airline saying that it prefers focusing on its current reorganization plan.

The two airlines have sent proposals and counterproposals during a recent bid from Frontier to take over bankrupt Spirit Airlines.

Spirit Airlines Inc. rejected a refreshed acquisition offer from rival budget carrier Frontier Group Holdings Inc., saying it would instead proceed with a planned restructuring in bankruptcy.

A merger of America's two largest budget airlines appears increasingly unlikely. Spirit Airlines on Thursday rejected Frontier Airlines' latest proposal for a merger, which would have helped bring the Florida-based carrier out of bankruptcy to join forces with its top competitor.