JetBlue Airways Corp. is continuing its quest to buy Spirit Airlines Inc., increasing its offer and strengthening its commitment to divest itself of assets to get regulatory approval for the deal.

JetBlue  JBLU, +5.30% on Monday increased its offer to $33.50 in cash per Spirit share SAVE, +2.11%. Previously, it had offered $31.50 per share.

Spirit is weighing whether to go ahead with a planned acquisition by Frontier Group Holdings Inc. ULCC or to accept JetBlue’s offer. The budget airline was supposed to hold a shareholder vote on the Frontier deal earlier this month, but postponed it to negotiate with both its suitors.

JetBlue’s move is the latest development in what has become a public negotiation. JetBlue and Frontier both consider Spirit to be important to their ability to grow and go up against the bigger airlines that dominate the industry. Either deal would create the fifth-largest U.S. airline.