AT&T is rallying its already massive lobbying efforts in Washington D.C., to get regulatory approval of its plan to buy Bellevue-based T-Mobile USA for $39 billion.

The WSJ reports that AT&T has a sizable lobbying army in D.C., with 93 lobbyists working its behalf. AT&T spent $15.5 million to lobby the federal government last year, the WSJ reports.

Still, gaining regulatory approval from the Justice Department’s antitrust division and the FCC is no slam-dunk.

The Obama Administration has said it plans to be tough on potential mergers such as the one between AT&T and T-Mobile, which would create the largest wireless company in the U.S. in an industry that already is highly concentrated among a handful of players.

In AT&T’s favor is a skillful lobbying army. AT&T also is hoping that its claim that the deal to acquire T-Mobile would expand broadband to rural America will resonate with regulators and policy makers.

Meanwhile, AT&T rivals are voicing concerns with the deal.

FierceWireless has a timely post about a forum with top executives from the three big U.S. carriers -- Sprint CEO Dan Hesse, Verizon Wireless CEO Dan Mead and AT&T President Ralph de la Vega. (T-Mobile CEO Philip Humm bowed out because of the pending deal with AT&T).

The trio were speaking at a wireless industry association event in Orlando. Here is a response from Sprint's Hesse:

“I do have concerns that it would stifle innovation and too much power would be in the hands of just two,” Hesse replied, a comment that drew applause from those in the audience likely aligned with AT&T and T-Mobile’s smaller rivals.

The WSJ quotes John Briggs, an antitrust lawyer at Axinn, Veltrop & Harkrider, saying the deal faces a “massive regulatory review.” Briggs gave it “a 50-50 chance of not getting through.”