AT&T hasn’t filed for approval for its proposed merger with T-Mobile yet, but the lobbying fight has already begun. So far, we’ve heard from the company that stands to lose the most if the deal goes through— Sprint — and from its far larger rival.

Sprint made an official statement Tuesday opposing the plan. The press release echoed the sentiments of Sprint chief executive Dan Hesse’s comments last week at the CTIA Wireless conference in Orlando.

In the statement, Sprint’s senior vice president of government affairs, Vonya McCann, urged the federal government not to approve the merger. A merger would entrench a mobile duopoly between AT&T and Verizon, she said, and the new company would be three times the size of Sprint, its nearest national competitor.

“Sprint will fight this attempt by AT&T to undo the progress of the past 25 years and create a new Ma Bell duopoly,” McCann said.

AT&T issued the following response, which recaps many of its arguments for the merger:

“The U.S. wireless market is intensely competitive with five or more competitors in 18 of the top 20 markets.  The AT&T  T-Mobile merger will improve quality for consumers, provide a near-term solution to spectrum exhaust, and expand the availability of LTE to 95% of Americans, spurring innovation and economic growth.”

When AT&T merged with SBC, it filed its merger approval paperwork three weeks after announcing the deal.

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