As we head into the final stretch of regulatory review for the pending $45 billion of Comcast and Time Warner Cable — and with the Dept. of Justice possibly prepping to block the deal — a group of U.S. Senators has written to U.S. Attorney General Eric Holder and FCC Chair Tom Wheeler urging them to prevent these two companies from getting hitched.

The letter [PDF] — signed by Senators Al Franken (Minnesota), Ed Markey (Massachusetts), Bernie Sanders (Vermont), Ron Wyden (Oregon), Richard Blumenthal (Connecticut), and Elizabeth Warren (Massachusetts) — raises numerous concerns that have been repeatedly brought up by opponents of the merger.

“Since the proposal was announced last year, we have from consumers across the nation,” states the letter, “all of whom fear that the deal would harm competition across several different markets and would not serve the public interest.”

The senators say these concerns “center on the undeniable reality that the combined Comcast-TWC would be the overwhelmingly dominant cable and broadband Internet provider in the nation and control much of the programming that Americans watch.”

With a merged Comcast/TWC controlling 57% of broadband and 30% of cable, the combined company would, according to the letter, “have an ability to defeat competing TV and Internet companies and stifle American innovation across the industry.”

Given that Comcast owns a major broadcaster and content provider in NBC Universal, the senators say an even bigger Comcast would “have incentives and means by which to extract higher prices from other multichannel video programming distributors and prioritize its own programming over that of competitors.”

The lawmakers say they have also heard from constituents “who are rightfully frustrated about their increasingly high cable and Internet providers dominating the market, consumers are often left with little choice but to pay the price a given provider demands and have little say over what content is made available to them.”

The merger will “only make things worse for consumers,” claims the letter.

“As the FCC and DOJ finalize their reviews of Comcast’s proposed acquisition of TWC, we urge you to defend American competition and innovation and ensure that Americans have affordable access to high-quality telecommunications services,” it concludes. “We hope you’ll take a stand for U.S. consumers and businesses and reject Comcast’s proposed acquisition of TWC.”

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