Sinclair Broadcast Group's headquarters in Hunt Valley, Md. (Steve Ruark/AP)

Norman J. Ornstein is a resident scholar at the American Enterprise Institute and co-author of “One Nation After Trump: A Guide for the Perplexed, the Disillusioned, the Desperate, and the Not-Yet-Deported.”

The foundations of the U.S. political system have recently come under unprecedented threat, centered around ma­nipu­la­tion by foreign powers — notably, the insidious role of Russian interference in our public debate — and the increasing domination of domestic news organizations by a small number of rich players.

But one particular challenge, involving Sinclair Broadcast Group and local television ownership, has gone almost unnoticed.

For many decades, the vigilance of the Federal Communications Commission has kept deep-pocketed players, including owners of newspapers and other important media, from attaining dominance over local television markets. But over the past year, the FCC weakened those rules. Fewer local media owners means less local news coverage.

Now, the proposed acquisition of Tribune Media by the Sinclair Broadcast Group is under consideration by the FCC and the Justice Department. Approval would likely trigger a hemorrhage in local reporting and voices and a sharp decline across much of the nation in balanced coverage of politics and government.

The proposed merger would be by far the largest in the history of local TV, adding up to 42 stations — including in New York City, Los Angeles, Chicago, Philadelphia, Dallas, Denver and other top-20 markets — to the Sinclair empire. These would join the 173 stations Sinclair already owns, including outlets in other big cities such as Baltimore, Minneapolis, Seattle, St. Louis and the District, plus stations in key electoral states such as Ohio, Pennsylvania and Wisconsin.

Congress limits a single broadcaster to covering 39 percent of the country, but due to an arcane rule adopted before cable and satellite became the dominant way that Americans receive broadcast TV, ultra-high-frequency stations get counted at only 50 percent of their coverage. Sinclair, which owns many UHF stations, would have ended up covering a staggering 72 percent of the national audience if approved as initially proposed — an action that would be hotly disputed by many in Congress who believe this would breach the law. Adding to the problem are Sinclair’s numerous “sidecar” agreements, a controversial industry arrangement that allows companies to bypass ownership limitations by outsourcing management, as well as much content, to another station in the same market.

In theory, media outlets owned by megaconglomerates will not necessarily ignore local interests. The real question is whether owners interfere in the content of the outlets, either to promote and protect business interests or to tilt news coverage in a slanted, ideological direction. Sinclair has frequently been accused of the latter, via “must-run” programming mandates that tilt heavily toward the right — including recent promotional inserts requiring its anchors to lament “false news.” The company maintains that such segments make up only a tiny fraction of programming and provide “a viewpoint that often gets lost in the typical national broadcast media dialogue.” But they directly contravene the localism principle at the core of the Communications Act.

The Sinclair merger has been opposed by a slew of individuals, media companies, members of Congress, state attorneys general, and newspapers and other media outlets. Importantly, these objectors range across the ideological spectrum from conservative cable news networks to liberal public interest organizations.

Sinclair president and chief executive Chris Ripley has defended the duopolies the company has in many local markets, arguing that they create “efficiencies” that ultimately improve local coverage. And the FCC, led by Chairman Ajit Pai, appears ready to approve the merger — assuming Pai escapes an investigation by the agency’s inspector general into whether he has shown favoritism toward Sinclair. Meanwhile, the Justice Department is negotiating with Sinclair and may permit the merger if the company agrees to divest several stations.

Sinclair did announce last month that it would sell stations in Chicago, New York (for an absurdly low price of $15 million ) and nine smaller markets. But even though selling these stations would on the surface significantly reduce Sinclair’s national coverage — Sinclair claims it would take it back under the 39 percent cap — its UHF discount and sidecar agreements in New York and Chicago to a family trust and a close Sinclair business associate, respectively, make that claim laughable.

The core principles undergirding the Communications Act are localism, diversity and competition. Approval of this merger, along with erasure of the previous limits on ownership, would open a floodgate, likely leading to more mergers by media conglomerates, whether liberal or conservative. This would mean more monopolies or oligopolies in broadcast news, which is a primary source of information for a significant share of Americans — those older, poorer and more rural citizens who do not have access to cable or satellite television.

This merger would be a major setback for America’s media and electoral process. And it is not an exaggeration to predict that it would signal the end of local TV as we know it.