Comcast plans to launch mobile Internet in Portland , Ore., over Clearwire’s WiMAX network by midyear, placing it among the first of Clearwire’s joint venture partners to resell the mobile WiMAX service.

The company will buy mobile WiMAX at wholesale prices and resell it under its own name, likely offering it as part of a quad play bundle comprised of television, phone and fixed Internet, COO Stephen Burke told The Oregonian on Friday. Comcast has $1 billion invested in Clearwire.

Company officials could not be reached for comment before press time, but the move comes as cable operators seek to fend off fresh competition from carriers like Verizon Communications and AT&T, who have released competing bundles over fiber optic networks. The paid television service market is saturated, but mobile data is a growth market that cable hopes to get a share of before carriers launch competing 4G networks.

Clearwire recently replaced CEO Ben Wolff with industry veteran Bill Morrow, moving Wolff to co-chairman. The company has defied widespread speculation that it lacked the capital for a swift WiMAX network deployment, announcing that it would burn through $1.5 billion to $1.9 billion in 2009 to build out its network.

The company says it will expand its mobile WiMAX network to cover 120 million people in 80 markets in 2010, a slightly lower prediction from last year’s forecast of 140 million.