By DAVID KOENIG and MICHELLE CHAPMAN
AP Business Writers
Spirit Airlines’ board still supports Frontier Airlines’ $2.9 billion takeover bid for the airline, saying it determined JetBlue’s competing $3.6 billion offer isn’t a superior proposal. Spirit said Monday that it’s concerned regulators won’t approve a deal with JetBlue. Last month, Spirit said it believed JetBlue’s offer could reasonably turn out to be the better of the two bids. But Spirit is changing its tune after a review of the regulatory situation. The big stumbling block for a JetBlue takeover is JetBlue’s current partnership with American Airlines in the Northeast, which already faces a lawsuit from federal and state regulators.