Just when it seems Sprint might be getting off the mat, along comes AT&T throwing another punch.

AT&T has asked the Federal Communications Commission to halt the merger of Sprint's WiMAX division with Clearwire, another blow to the creation of the companies' planned $15 billion 4G network. In April, Sprint announced that the launch of its XOHM service was delayed, and that they're still looking to get it going later this year.

But Brighthand reports that AT&T is crying foul and contends the deal isn't under enough scrutiny, with the emphasis on a number of spectrum licenses held by Sprint and Clearwire.

Responds Sprint:

A spokesman for Sprint said that the companies have documented for the FCC on a county by county basis how much spectrum they would hold after the merger, and that nearly 50 public entities had filed similar comments in support of the proposed merger.

We'll keep an eye on this one.