In a statement, Mike Lee, R-Utah., and Amy Klobuchar, D-Minn. — chairman and ranking Democrat, respectively, of the Judiciary Subcommittee on Antitrust, Competition Policy and Consumer Rights — said AT&T's acquisition of Time Warner "would potentially raise significant antitrust issues" that the panel would "carefully examine."

AT&T Chairman and Chief Executive Randall Stephenson announced the $85 billion deal Saturday as "a great fit" that will combine the "world's best premium content with the networks to deliver it to every screen."

Among those new properties are HBO, Turner Broadcasting System and Warner Bros., which would give them ownership of Cinemax, CNN and DC Comics, to name a few.

Last year, AT&T completed the purchase of DirecTV, the country's largest satellite television provider.

In an interview with NBC News, Klobuchar pointed to past mega-media acquisitions — including the purchase of NBCUniversal by Comcast in 2011 and of Time Warner Cable by Charter Communications — and said the "sheer volume" of the deal should give regulators pause.

"This proposal is more than all of those," she said, adding: "There's been so much consolidation."

Klobuchar said she wants to ensure that the deal doesn't roll back Time Warner's ability to offer competitive products, such as HBO Go, the subscription streaming service.

"That's an alternative to a big bundle of cable," Klobuchar said. "Will they eliminate incentives?"

A Time Warner spokesman declined to comment.

In a statement, AT&T's senior executive vice president and general counsel, David McAtee, said the company "look[s] forward to discussing the many benefits of this transaction with our regulators."

"In the modern history of the media and the Internet, the U.S. government has always approved vertical mergers like ours, because they benefit consumers, strengthen competition, and, in our case, encourage innovation and investment," McAtee said.

Separately, Sen. Tim Kaine, D-Va., the Democratic vice presidential nominee, also expressed skepticism about the merger, saying on NBC's "Meet the Press" that he is "generally pro-competition."

"Less concentration .. is generally helpful, especially in the media," Kaine said.