According to a copy of a letter to the chairs of the House and Senate Commerce and Judiciary Committees, which among them oversee communications issues, including mergers, they warn of the "growing power" of media conglomerate and the leverage they say that gives them over the public's access to content.
They call that leverage unprecedented and a threat to "the very freedom of expression cherished by people regardless of political persuasion."
Signing on to the letter were Cinemoi, INSP, theblaze, RideTV, One America News Network, and MAVTV Motorsports.
They argue the deal could cripple program diversity, which is why they want Hill hearings on the impact of the merger. "As independent programmers, we stand together in our concerns over further consolidation in the video programming marketplace," they said.
With the addition of Tribune stations and the recent restoration by the FCC of the UHF discount, Sinclair would be able to reach 72% of TV households, which the programmers say would give them the power to exercise dominant influence over content, a power they say Sinclair-Tribune would be certain to use.
Sinclair has been the target of allegations of political favoritism toward conservative views.
"Because this transaction is enabled by regulatory action [eliminating the UHF discount], it should be carefully reviewed by the House Energy and Commerce and Senate Commerce committees in their oversight capacity," they told the FCC.
The letters were sent to House Energy & Commerce Committee chairman Greg Walden (R-ore.), House Judiciary Committee chairman Bob Goodlatte (R-Va.), Senate Commerce chairman John Thune (R-S.D.) and Senate Judiciary Committee chairman Charles Grassley (R-Iowa).
Back in May, Sinclair Broadcast Group struck a deal to buy Tribune's 42 stations for $3.9 billion.
The FCC must still rule on whether the transfer of the station licenses are in the public interest.