Sinclair's chief executive, Chris Ripley, has called Pai's relaxation of media ownership rules a "landmark" development for his company and the industry.
Pai's office declined to comment on the report, but the chairman has denied his deregulatory agenda was meant to benefit any one company.
The FCC's inspector general is conducting an investigation into a series of FCC actions previous year, and how they benefited Sinclair Broadcast Group in the midst of seeking regulatory approval for its acquisition of Tribune Media.
Pallone and Cummings pointed to the timing of decisions that impact Sinclair deals (such as its purchase of Bonten stations) and proposed deals (the Tribune acquisition), and said they wanted some answers.
And last April, two weeks before Sinclair announced their plans to purchase Tribune, the FCC tweaked the UHF discount, allowing one company to reach up to 78 percent of American homes, shattering previous ownership caps.
Pai's critics have noted that he has pushed through a number of deregulatory proposals that appear to clear regulatory obstacles from Sinclair's proposed expansion. "Considering the strong case for modernizing these rules, it's not surprising that those who disagree with him would prefer to do whatever they can to distract from the merits of the reforms that the FCC has adopted".
Free Press wants "Pai and any other FCC staff subject to this inquiry [to] recuse themselves from all dealings related to Sinclair's proposed takeover of Tribune Media", González said.
After an investigation that took more than a year, an August 2016 report by the FCC IG found no evidence of improper coordination between then-Chairman Tom Wheeler and the White House on net neutrality regulation.
The Sinclair-Tribune merger is still under review by the FCC and the Department of Justice.
Sinclair's top lobbyist, a former FCC official, also communicated frequently with former agency colleagues and pushed for the relaxation of media ownership rules.
Pai is no stranger to the communications world. The office of the FCC's nonpartisan inspector general didn't comment on "the existence or the nonexistence of an investigation" to The New York Times. He has refused to turn over those communications to Congress. David Hunt agreed to conduct the investigation after it was requested in November 2017 by two Democratic lawmakers.
"If the merger is approved, the conservative broadcaster would be able to air politically biased programming to more than 70 percent of the United States population", Free Press said today.
FCC spokespeople were not available to comment on the status of that investigation or what the threshold for investigating a complaint is, though the FCC web site outlines the factors the IG considers in agreeing to investigate.
"It's doubtful the review will lead to a public report in the short term that would move the FCC's three Republicans to block the deal", Schettenhelm said.
Information for this article was contributed by Todd Shields of Bloomberg News.