âRarely is bigger better,â Jonathan Schwantes, a senior policy lawyer at Consumers Union, the policy arm of Consumer Reports, said. âFor us, itâs all about consumers having choices, good choices.â
Politicians of all stripes â from Donald J. Trump and Hillary Clinton to lawmakers from both sides of the aisle â have also weighed in with doubts about the prospect of more consolidation. In a statement, the top Republican and Democrat on the Senate Judiciary Committeeâs antitrust subcommittee said they planned to hold a hearing on the deal.
And even competitors like Disney quickly chimed in, urging regulators to pay close attention in their review.
At issue is whether AT&T, with over 100 million subscribers across its wireless, broadband and DirecTV offerings, will somehow favor its own customers when it comes to HBO, CNN and Warner Bros. properties like the Batman and Harry Potter franchises.
Some consumer rights advocates also questioned how AT&T will use the viewership data that it gathers from its subscribers, particularly if the Time Warner acquisition drives more consumers to AT&Tâs services.
In an interview on Sunday, the chief executives of both AT&T and Time Warner stressed that they had no intention of limiting Time Warnerâs content solely to the combined companyâs offerings.
âWeâre buying what I think is the premium content creator, developer and aggregator on the planet,â said Randall L. Stephenson, AT&Tâs chief executive. âTo buy that and then constrict how that content is distributed doesnât make a lot of sense to me. Itâs almost illogical.â
That has been a longstanding concern about Comcastâs ownership of NBCUniversal, which the Federal Communications Commission approved in early 2011 under several conditions, including ensuring that NBCUniversalâs programming was available to all video service providers and at fair terms; safeguarding the access of Netflix and other online video competitors to Comcastâs network; and protecting local programming.
Some consumer advocates have questioned how effectively regulators have enforced the conditions of the NBCUniversal deal. Still, Mr. Schwantes of Consumers Union said that the programming limitations were the most crucial aspect of the F.C.C.âs ruling and regulators should keep them in mind as they decide whether to allow the Time Warner takeover.
Of special interest is that, unlike Comcast, AT&T is a truly national service provider, as well as an international one, given its growing presence in Mexico and Latin America thanks to previous acquisitions.
âProgramming is what worried people the most,â Mr. Schwantes said. Referring to the F.C.C.âs limitations on the NBCUniversal deal, he added, âI donât think itâs lowered prices, but thanks to those conditions, we still have an online video distribution marketplace.â
Politicians from both parties stressed that they were concerned about any limitation of consumer choice.
âThis oligopolistic realignment of the American media along ideological and corporate lines is destroying an American democracy that depends on a free flow of information and freedom of thought,â Peter Navarro, a senior economic adviser to Mr. Trump, said in a statement on Sunday.
A spokesman for Mrs. Clinton told reporters that she âcertainly thinks regulators should look atâ the deal.
Senator Bernie Sanders wrote on Twitter that the government should âkillâ the deal, citing the prospect of higher prices and fewer choices.
And Mike Lee, the Republican chairman of the Senateâs antitrust subcommittee, and Amy Klobuchar, the ranking Democratic member of the subcommittee, said in a joint statement that the transaction âwould potentially raise significant antitrust issues.â
Both AT&T and Time Warner professed little worry that their deal would fail because of regulatory interference. The transaction provides for a $ 500 million breakup fee payable to Time Warner if the takeover is blocked on antitrust grounds, a relative pittance for a merger of this size.
Both Mr. Stephenson of AT&T and Jeffrey L. Bewkes of Time Warner stressed that during nearly three months of deal negotiations, the idea driving the talks was that Time Warner could help AT&T build out its own video streaming service. That service, called DirecTV Now, is Mr. Stephensonâs response to the migration of consumers toward mobile and online video watching and away from traditional cable packages.
âWeâre seeing ever-faster innovation,â Mr. Bewkes said in the interview, adding that the rise of competing services, to which his company would continue selling its offerings, would maintain choice for consumers.
In particular, mobile video watched on smartphones or tablets will be crucial for future viewers, according to Amy Yong, an analyst at Macquarie Group. Even as Netflix, Amazon, AT&T, Verizon and others seek to figure out broadband-based video, mobile stands as the next hurdle to surmount.
âI think it all comes down to mobile video,â she said, adding that no one has truly figured it out yet. âItâs not just the type of content, but also where consumers watch it.â
But Mr. Stephenson and Mr. Bewkes also stressed that the additional data that they could collect from video subscribers could bolster their businessesâ advertising initiatives. Viewership information would allow for better targeting of ads while also shaping the kinds of content that Time Warner produces.
The executives said better advertising could yield more money that would then go to further pay for additional content.
âIt allows us to recoup the cost of content through both subscription revenue and also through advertising,â Mr. Stephenson said.
Ms. Yong said that in markets served by Comcast, NBC shows tend to enjoy higher ratings, thanks to both the better viewership data available and more robust promotion.
The Center for Digital Democracy, a consumer advocacy group, described it in more ominous terms.
âFor consumers, it means these megacompanies are going to track them across their offline and online daily experiences,â Jeffrey Chester, the centerâs executive director, said. âOn one hand, theyâre going to be able to access a wide variety of Time Warner-branded content on any device, but they should expect that theyâre going to be losing a lot of personal privacy as a result.â