Midwest Air Group is considering an acquisition by TPG Capital and "one or more partners

Midwest Airlines parent ," including a "passive investment" from Northwest Airlines, after rejecting a final offer from AirTran Airways parent AirTran Holdings. Northwest said it "will not participate in the management or control of Midwest should TPG acquire Midwest," but AirTran said Northwest's involvement "will surely raise antitrust concerns." Midwest said it and TPG expect to "execute a definitive merger agreement no later than Aug. 15."