The Biden administration sued on Tuesday to block JetBlue Airways' $3.8 billion purchase of Spirit Airlines, saying the deal would reduce competition and drive up air fares for consumers. The Justice Department said the tie-up would especially hurt cost-conscious travelers who depend on Spirit to find cheaper options than they can find on JetBlue and other airlines. Attorney General Merrick Garland was scheduled to hold a news conference to announce the lawsuit — a sign of the importance that the administration places on stopping further consolidation in the airline industry.