Two Dutch circuits are reportedly "still in the race" to secure a place on the 2020 grid.
RTL Nieuws, a Dutch broadcaster, has leaked a letter from F1 chief executive Chase Carey to officials at the Zandvoort circuit.
The letter said that if Liberty Media and Zandvoort do not conclude a 2020 race deal by 31 March, there are no other Dutch circuits also in the running.
But Assen promoter Lee Van Dam told De Telegraaf newspaper that his team is "keeping our spirits up".
"We are definitely still in the race to bring formula one in 2020," he insisted.
"We had contact with FOM last week and we will be at the table again soon," Van Dam said. "They are straight with us, so if we were no longer a party, they would have told us respectfully."
Bruno Bruins, a federal minister in the Netherlands, wrote in a letter to parliament that the government "will not contribute financially" to a Dutch grand prix.
Reports say Zandvoort had asked the federal government for an annual contribution of EUR 7 million. But Bruins said the prospect of a Dutch grand prix "does not justify the use of tax resources".
"This is a commercial sporting event where the rights are in the hands of a listed American company," he added, explaining that government funds are therefore "neither necessary nor justified".
However, Bruins said Zandvoort is in talks with a number of Dutch companies, with existing F1 sponsor Heineken reportedly among those interested.
The minister also claimed that Zandvoort already has an "agreement in principle" with Liberty Media for three years between 2020-2022.
Bruins said the government is willing to support the grand prix in other ways, because it is a "nice initiative".