California and three other states have joined a federal lawsuit aimed at blocking JetBlue's $3.8 billion purchase of Spirit Airlines, which is scheduled for trial this fall.

New Jersey, Maryland and North Carolina also joined in an updated version of the complaint that was filed Friday in federal district court in Boston.

The Biden administration argues that the deal would reduce competition and drive up prices for airline consumers by eliminating Spirit, which is known for low fares. JetBlue argues that the deal will help consumers by making the New York-based airline a stronger competitor against American, Delta, United and Southwest.

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The original lawsuit was brought earlier in March by the U.S. Justice Department, Massachusetts, New York and the District of Columbia against JetBlue Airways and Spirit. Attorney General Merrick Garland led a press conference to announce the lawsuit, a signal of the importance that the Biden administration attaches to the case as part of its campaign against consolidation in many industries.

A federal judge scheduled the trial to begin Oct. 16 in Boston.