Spirit Airlines and Frontier Airlines agreed Wednesday to abandon their merger proposal, opening the way for JetBlue Airways to acquire Spirit.

Spirit, the largest budget carrier in the United States, said it was still in discussions with JetBlue "and expects to provide a further update in the near future."

The decision by Spirit and Frontier to terminate their deal was announced while Spirit shareholders were still voting on the proposal. It was apparent that despite the support of Spirit's board, shareholders were prepared to reject the Frontier deal.

The Frontier offer was worth more than $2.6 billion in cash and stock, far short of JetBlue's all-cash bid of $3.7 billion.