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

Frontier Airlines is making another offer to merge with bankrupt Spirit Airlines, less than two years after a previous plan fell through.

Low-cost air carrier Frontier Airlines is adding three new routes this spring, connecting more destinations across the U.S. and Caribbean, beginning in May. On May 1, the airline will launch new daily nonstop service between Washington Dulles International Airport (IAD) and Las Vegas’s Harry Reid International Airport (LAS).

IT issues at Frontier Airlines triggered a brief ground stop at all of the U.S. budget carrier's destinations on Thursday evening, according to an advisory from the U.S. Federal Aviation Administration.

Rather than accept Frontier’s offer, Spirit said it will stick to its current plan to emerge from Chapter 11 bankruptcy.

Frontier Airlines is adding a new Caribbean destination to its flight lineup from Cincinnati/Northern Kentucky International Airport. The ultra-low-cost carrier will start weekly flights to the Dominican Republic starting Saturday, May 17.