The merger between Comcast and Time Warner Cable appears "too big to sail" past federal antitrust regulators without "serious, serious scrutiny," Reed Hundt, former chairman of the Federal Communications Commission, told CNBC on Thursday.
"The FCC and the Department of Justice probably have not green-lighted the deal already," he said on "Squawk on the Street." "I don't know what the companies have said to them. I would be very dubious that the deal has been green-lighted. It's too early to say the deal will be approved without serious scrutiny."
Comcast's acquisition deal for Time Warner Cable, an all-stock transaction worth $45.2 billion, was announced officially Thursday morning. Comcast CEO Brian Roberts told CNBC that he's confident that regulators will approve the merger, despite concerns about the two biggest U.S. cable providers joining forces.
The regulatory process is likely to focus on the combined companies' massive share in broadband, Hundt said, adding that the companies might have about half of all cable video subscribers in the U.S. and even more broadband Internet subscribers.
That will be a point of concern for FCC Chairman Tom Wheeler, said Hundt, who chaired the commission from 1993 to 1997.
The FCC will press on whether the combined company would "bottleneck" Web connections or open them up to faster speeds for less money through investments in advanced broadband networks, he said.
(Re/code: Deal faces long antitrust review)
"That's the question they're going to be asked by the FCC for sure, because Tom Wheeler is committed to making sure the Internet is open," Hundt said. "And he doesn't mean a thin little pipe. ... He means a big, big, huge roadway to the broadband future."
(Disclosure: Comcast is the owner of NBCUniversal, the parent company of CNBC and CNBC.com.)
—By CNBC's Jeff Morganteen. Follow him on Twitter at @jmorganteen and get the latest stories from "Squawk on the Street."