Sprint Nextel is taking its battle against AT&T’s acquisition of T-Mobile to the states, starting with a request for the West Virginia Public Service Commission to investigate and block the deal.

In a filing Monday with the state commission, Sprint Nextel said the agency has a mandate to ensure mergers don’t harm the public.

“Clearly the interest of the public in this state will be adversely affected by the proposed merger because it is anticompetitive and will hurt consumers by raising prices, restricting innovation and limiting choices of wireless providers,” Sprint said in its filing.

Sprint, the nation’s third-largest wireless carrier by number of subscribers, has emerged as the most vocal opponent of the $39 billion deal. It says 80 percent of all wireless consumers will hold AT&T or Verizon Wireless plans, creating a duopoly in the market.

A Sprint spokesman said the company will likely file similar petitions in other states where AT&T is required to gain approval for the transfer of T-Mobile licenses.

AT&T spokesman Michael Balmoris said the merged company would significantly expand mobile broadband access to the state of West Virginia. It has promised to increase deployment of mobile Internet service beyond what it would have as just AT&T.

“Anyone who looks at our current plan to deploy 4G LTE in West Virginia versus our deployment plan after the merger can see the tremendous benefits this transaction will bring to West Virginia consumers,” Balmoris said.

It will be a difficult battle on the state level for Sprint. AT&T has many more employees than Sprint that lobby state utilities commissioners, observers said.

And it is early still in the merger process. The FCC has only started its review of the merger three weeks ago. The Justice Department is collecting information from AT&T, T-Mobile and competitors to look into possible antitrust implications of the transaction.

Related stories:

Consumers give FCC an earful on AT&T, T-Mobile merger

AT&T executive Jim Cicconi on the merger