(Reuters) -Spirit Airlines would start talks with JetBlue Airways Corp on its $3.6-billion offer, the budget carrier said on Friday as it could likely lead to a “superior proposal” to the one from Frontier Group Holdings.

JetBlue made an unsolicited offer of $33 per share in cash earlier this week, beating a near $25 per share cash-and-stock bid from Frontier made in February.

JetBlue and Frontier did not immediately respond to requests for comment. Spirit said the discussions with JetBlue was in keeping with the terms of the company’s merger agreement with Frontier.

Denver-based Frontier and JetBlue are in a tug of war for Florida-based Spirit to capture a larger share of the leisure market and better compete with legacy carriers.

Either deal is sure to invite a close scrutiny from U.S. antitrust authorities, who have taken an aggressive stance under the Biden administration toward deals that reduce competition and raise prices.

(Reporting by Nilanjana Basu and Abinaya Vijayaraghavan in Bengaluru; Editing by Arun Koyyur)