The possibility of a merger between Spirit Airlines and Frontier Group will be a reality for at least another week.
Spirit has pushed back a shareholder vote on Frontier's merger offer for the budget carrier until next week.
Spirit shareholders were due to take their vote at a special meeting on Thursday.
The meeting will be held on July 8.
The vote is not the first time that it has been delayed. A vote that was scheduled for June 10 was also postponed.
The delays suggest that Spirit doesn't have the votes of shareholders to back the deal.
Spirit Airlines has been the subject of a bidding war between Frontier Group and JetBlue Airways.
Spirit signed a cash-and-stock deal with rival Frontier in February, and JetBlue jumped into the mix in April with an all-cash offer.
Spirit said the U.S. regulators would stop that deal, but JetBlue's bid is higher.
The ISS of the Frontier Group has reversed its opinion about a deal after the advisory firm, Institutional Shareholder Services Inc., reversed its offer for Spirit Airlines.
Spirit shareholders are urged to vote on a proposed merger with Frontier's parent company, according to ISS.
The advisory firm asked Spirit shareholders not to reject Frontier's offer, saying JetBlue's competing offer of $30 a share is superior from a financial standpoint.
Spirit said last week that Frontier raised its cash offer by $2 per share.
ISS said the current offer from Frontier matches the $2.00 increase in JetBlue's offer price, and also provides a higher prepayment of $2.22 per share, compared to $1.50 per share from JetBlue.
Frontier also increased its reverse termination fee to Spirit by $100 million to $350 million.
On Wednesday, Spirit said its board would engage with both the bidders about their offers.