Frontier and Spirit Airlines will once again try to merge, only months after the Biden administration won a key antitrust court battle to block an attempt by JetBlue to buy Spirit. A combination of the two ultra-low-cost carriers would produce the country’s fifth largest airline,

Spirit, which filed for bankruptcy protection last year, says it has rejected the new Frontier overture but would be open to a higher offer.

Budget carrier Frontier Airlines announced on Wednesday that it has made another bid for fellow discount carrier Spirit Airlines, which is in bankruptcy, for an undisclosed sum.