The EU commissioner for the digital economy has threatened legal action after Polish MPs approved a law giving the government direct control over top appointments in public broadcasting.
The commissioner, Guenther Oettinger, said he would raise the issue at a meeting of the commission on 13 January. "There are solid grounds for us to activate the rule of law mechanism and put Warsaw under monitoring,” he said.
Under the EU's rule of law mechanism, adopted last year, the Commission can escalate pressure on a member state to amend any measure that is considered a "systemic threat" to fundamental EU values.
On Saturday the directors of four channels of TVP - Poland's public service television - resigned in protest at the new law.
Among those resigning were the head of TVP Kultura Katarzyna Janowska and Tomazs Lis, one of Poland's most recognised journalists.
"No one can force Poland to shut its mouth. No one can force me to shut my mouth," Lis said.
Human rights groups and journalists' associations have come out in protest against the new regulation, including the European Broadcasting Union (EBU) and the Reporters Without Borders (RSF).
The media law has not yet taken effect - but President Andrzej Duda, an ally of the ruling Law and Justice Party (PiS), is expected to approve it this week.
Current media regulators will be replaced, and the treasury minister will exert direct control over the public channels' managers.
The PiS says new managers are needed at the top of state institutions because the previous centre-right Civic Platform party allowed corruption to flourish.
TVP has two main national channels, and operates regional services and the satellite network TV Polonia.
Public Polish Radio reaches just over half of the population, with four national radio stations and 17 regional stations.