(Reuters) – T-Mobile US Inc’s $26 billion deal to buy Sprint Inc banked on changes in wireless technology and media streaming to win U.S. antitrust approval, but the bet now looks precarious.

FILE PHOTO: A smartphones with Sprint logo are seen in front of a screen projection of T-mobile logo, in this picture illustration taken April 30, 2018. REUTERS/Dado Ruvic/Illustration

Growing skepticism from the U.S. Department of Justice’s antitrust staff over the impact of the merger on competition in the market will test the resolve of the companies to complete the deal that would see the top U.S. wireless carriers shrink to three from four.

While the Department of Justice has yet to reach a decision on whether to approve the deal, it is pushing Sprint