WARSAW, Poland — Nationwide demonstrations are planned across Poland Tuesday against a bill widely viewed as a effort by the country’s ruling nationalist party to silence an independent, U.S.-owned television broadcaster often critical of the government.

At stake in the bill’s passage is Poland’s reputation for media freedom and as a place for foreign companies to do business. If it passes it is also likely to strain relations with the country’s strategic ally, the United States.

Technically, the bill would prevent non-European owners from having controlling stakes in Polish media companies.

In practice, it would push the U.S. company Discovery Inc. to sell its controlling stake in the broadcaster TVN, which operates many channels — most notably TVN24, an all-news station. TVN also has a flagship evening news program on its main channel that is watched by millions daily.

The ruling party, Law and Justice, has long sought to nationalize the media sector, citing national security, and says the law would bring Poland into line with other European countries, including France and Germany, which limit foreign ownership in the media sector. Party lawmakers have recently argued it is needed to protect Polish media from being taken over by Russian, Chinese or Arab capital.

“We need to protect Poland against the entry of various entities from countries that are hostile to us,” said, Marek Suski, the head of a group of Law and Justice lawmakers who introduced the bill last month.

Its passage is unclear as a junior partner in the right-wing ruling coalition is opposed to the bill, though it could pick up votes from some far-right opposition lawmakers.

TVN24 is the leading source of independent broadcast news for many Poles. The station celebrated the 20th anniversary of its launch on Monday with a certain fanfare underlining concerns over its fate.

Demonstrations in support of the TVN broadcaster are planned in 78 cities and towns Tuesday evening, the day before parliament is scheduled to begin debating the bill. The protests are organized by the Committee for the Defense of Democracy, under the slogan “free media, free people, free Poland,” and supported by several press freedom and human rights groups.