Hollywood writers and representatives of movie and television studios kept talking past a midnight deadline into the early hours of Tuesday morning to try and stave off a strike that could black out TV talk shows and soap operas.
Variety reported late on Monday that there had been "cautious reports of movement on key issues" in the contract negotiations between the Writers Guild of America (WGA) and the Alliance of Motion Picture and Television Producers (AMPTP).
If there is no agreement, the 9,000-member Guild has said it is prepared to call for a stoppage and for picketing of the big TV and movie studios as early as Tuesday.
WGA members took part in Monday's May Day march in downtown Los Angeles, held in support of workers rights and union solidarity.
The two sides have imposed a media blackout on the talks, which are centered on the revolution in the television industry caused by the arrival of Netflix, Amazon and other streaming services - and a resulting sharp decline in the typical number of episiodes in a season of scripted comedy or drama, to around 10 from 22.
The WGA says its members, who are paid per episode, have suffered an average 23-percent drop in earnings in the past three years.
Royalties for shows sold on DVDs, streaming platforms and cable TV are also at issue, along with funding for the WGA's health plan.
The AMPTP represents entertainment giants Comcast Corp , Walt Disney Co, CBS Corp, Viacom Inc , Time Warner Inc and Twenty-First Century Fox Inc, which control TV and movie production in the United States.
If a strike is called, audiences would first see the impact on late night talk shows, which use teams of writers to pen topical jokes. Daytime soap operas would be affected next, but most TV network comedy and drama shows due for broadcast in the coming 2-3 months have already been written and filmed, network executives have said.
The last WGA strike in 2007/8 went on for 100 days. TV networks broadcast re-runs and more reality shows, while the cost to the California economy was estimated at $2.1 billion, according to the Milken Institute.