A federal judge told Aetna that it will have to wait until December to make its case in defense of its proposed $37 billion acquisition of Humana, rejecting the insurer's request for an earlier trial.

U.S. District Judge John Bates scheduled a two week trial to begin on Dec. 5, meaning he will likely issue a decision on the case in January.

In response to the U.S. Department of Justice's decision last month to seek to block its deal — along with a similar proposed merger between Anthem and Cigna — Aetna asked for a trial as soon as September, saying it needed to happen soon to keep the tentative deal between the two companies from falling through.