Maine Republican Sen. Susan Collins, who famously has issues with the Republican healthcare bill, also has some issues with the AT&T-Time Warner Inc. merger.

Collins said she thinks the merger could have a "significant, negative impact on competition and innovation," according to a letter to acting assistant attorney general Andrew Finch, a copy of which was obtained by Multichannel News.

Collins did not come out against the deal, but said DOJ needs to look carefully at its "potential impact on consumers and competition."

She said the merger could "create an opportunity" for AT&T to "favor HBO in marketing and packaging of premium content to its customers, discriminating against competitors."

The risk that the deal could "dramatically reduce consumer choice" in favor of AT&T's new "in-house brand" is real, she said.

Collins added that the merger could allow AT&T, which also owns DirecTV, to raise content costs to competitors like Dish, which would pass them along to her constituents. "Ultimately, consumers would lose," she said.

DOJ's antitrust review is the sole federal review. The FCC is not vetting the merger on public interest grounds because the deal does not involve any license transfers after AT&T and Time Warner structured it so no licenses were in play. Various states are also reviewing the deal.