By Diane Bartz
WASHINGTON (Reuters) - The judge overseeing the U.S. government's bid to stop health insurer Anthem Inc <ANTM.N> from buying Cigna Corp <CI.N>, who had been seen as favorable for the deal, has relinquished the case.
Judge Amy Berman Jackson of the U.S. District Court for the District of Columbia was named to hear the case after Judge John Bates asked that it be reassigned. Jackson was nominated to the bench in 2011 by President Barack Obama, a Democrat.
Bates will hear the U.S. Justice Department's challenge to Aetna Inc's <AET.N> purchase of Humana Inc <HUM.N>. He was originally assigned to both cases.
President George W. Bush, a Republican, had named Bates to the court in 2001. The judge had ruled against antitrust enforcers in 2004 when he allowed Arch Coal Inc <ACIIQ.PK> to buy Triton Coal.
Jackson also said in an order on Friday that she wanted to know what dates lawyers for the case were not available in December or January, indicating that she was contemplating a trial at that time.
This would be bad news for Anthem, which has stressed that it needs a decision by Dec. 31 to wrap up final approval from state regulators by April 30, 2017.
Christopher Curran, Anthem's lawyer, said at a hearing on Thursday that the failure to get approvals on time would doom the deal because Cigna would not agree to an extension. He called the April 30 deadline "real and hard and fixed."
Anthem said it did not matter which judge heard the case. "Anthem is extremely pleased that Judge Bates recognizes in his order Anthem's need for an expedited hearing regarding our acquisition of Cigna and we look forward to an expeditious resolution of the matter," the company said in a statement.
The change in court assignment came shortly after Bates said in a pretrial hearing on Thursday that it would be difficult for him to decide the Anthem case and Aetna's merger with Humana by the end of the year.
Aetna's stock was up 2.5 percent while Humana rose 2.6 percent. Anthem's stock was up less than 1 percent and Cigna's shares were down less than 1 percent.
The U.S. Department of Justice filed lawsuits in July to block the multibillion-dollar mergers, both of which were announced in July 2015. Anthem's planned purchase of Cigna is valued at $45 billion, while Aetna would pay about $33 billion for Humana.
If the mergers go through, No. 1 U.S. insurer UnitedHealth Group Inc <UNH.N> would rank second after Anthem. Aetna would be No. 3.
(Reporting by Diane Bartz; Editing by JS Benkoe, Lisa Von Ahn and Bernard Orr)