Formula 1 chairman Chase Carey insists that plans to hold a street race in Miami are still moving forward, but says it is taking time to reach agreement.
The initiative has been in doubt since the Miami city commission voted to indefinitely defer the plans in September in the face of local opposition to the cost and disruption involved in hosting the event.
In the meantime, F1 announced last week that a new race in Vietnam would be added to the calendar for 2020.
The lack of any mention of a prospective race in Miami had been taken as tacit admission that there was little hope of it going forward in the foreseeable future. But Carey insists that's not necessarily the case.
"The plan is to have a second race in the US," he is quoted as saying by Speed Week. "But we are not just dealing with Miami, even if we are convinced that it would be a great project.
"The negotiations are going on. When it comes to street circuits there are many interests that need to come together and it takes time."
F1 held a special 'F1 Live' event last month which had been designed to bolster support for holding a Grand Prix in the city.
"The fan festival helped," Carey confirmed. "Everyone thought the event was great. It was a positive step towards the race."
There had been suggestions that Carey might lower the hosting fees F1 charges for staging an event in order to get the Miami Grand Prix off the ground, or that Formula 1 might take on the role of local promoter of the race in order to reduce opposition to the plans.
Carey confirmed that a number of alternatives were still being looked at. "We will not turn the model upside down," he vowed. "But if the return justifies the risk, let's look at it."
The Vietnam announcement and ongoing push for a race in Miami comes amid claims that some of the sport's oldest and most popular venues might lose their spot on the calendar.
Silverstone has already exercised a break clause in its contract meaning that next year's British Grand Prix might be the last held at the circuit. Brazil, Hockenheim and Monza are also reported to be under threat.
"We want to keep the races with a long history," F1 commercial boss Sean Bratches insisted this week
"They are important for the sport and for the fans," he is quoted as saying by French commercial radio network RTL. "But in terms of race locations, nothing in this sport is unchanging. We are a business after all."
Plans laid down by Carey's predecessor Bernie Ecclestone to hold a second US event in New Jersey in 2013 also eventually came to nought, leaving just the one F1 race per year in the country at the Circuit of the Americas in Austin, Texas.
Ecclestone recently revealed that he had decided against holding a race in Vietnam before he was ousted by F1's new owners Liberty Media at the start of last year.
"I did not want to have a Grand Prix in an area where we already have very good promoters," Ecclestone explained.