WASHINGTON – The chairman of the Federal Communications Commission has come out against the merger of cellphone giant AT&T and T-Mobile USA.

Julius Genachowski made his position known in a document he circulated to fellow commissioners Tuesday.

Genachowski recommended sending AT&T Inc.’s proposed $39 billion takeover of T-Mobile to an administrative law judge for review and a hearing. That’s what the FCC does when it opposes a merger.

The hearing, which could lead to a rejection of the deal, was proposed in an order that Genachowski offered Tuesday for consideration by the full FCC, officials who declined to be identified said in a briefing with reporters. Agency staff had found the proposed merger would significantly diminish wireless competition, one official said.

The hearing would take place after the resolution of a Justice Department court challenge to the transaction, the FCC officials said. The antitrust case is scheduled for trial in February.

AT&T is “reviewing all options,” Larry Solomon, senior vice president of corporate communications, said in an e-mailed statement.

“The FCC’s action today is disappointing,” Solomon said. “It is yet another example of a government agency acting to prevent billions in new investment and the creation of many thousands of new jobs at a time when the US economy desperately needs both.”

The purchase of Bellevue, Washington-based T-Mobile would eliminate one of four national U.S. wireless carriers. AT&T has said the transaction would help it bring wireless high-speed Internet service to more people.

“Significant Obstacle”

The deal would lead to massive job losses as AT&T realizes savings, and the record at the FCC doesn’t show the merger would significantly spur the spread of wireless high-speed Internet service, an agency official said. Wireless concentration would increase in 99 of 100 markets, the official said.

The FCC can designate a transaction for a hearing, which is akin to a trial, when it cannot find the deal is in the public interest. The administrative law judge presiding over the hearing delivers an initial decision that goes to agency commissioners for a vote.

Commissioners may vote in coming days on Genachowski’s proposal.

“A hearing could go on for six to 12 months,” Andrew Lipman, a Washington-based partner with Bingham McCutchen LLP, said in an interview. “It’s certainly a significant obstacle and roadblock.”

(Bloomberg news contributed to this report.)

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