The Biden administration sued on Tuesday to block JetBlue Airways from buying 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, a budget carrier, 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.

JetBlue and Spirit have anticipated the government challenge for weeks. The government had previously requested additional documents and depositions about JetBlue's proposed $3.8 billion purchase of Spirit, the nation's biggest budget airline. Negotiations over a possible settlement failed.