United States Grand Prix circuit chiefs have been left bemused by remarks from Bernie Ecclestone in which he cast doubt on next year's race in Texas.
Formula 1 boss Ecclestone described negotiations as "an uphill struggle".
Steve Sexton, president of the Austin circuit, said: "Our funding is secured and construction is on schedule, so we don't understand these comments.
"He has expressed great interest in the Austin race and in expanding the F1 brand into the US."
Ecclestone said on Saturday: "Austin? I wouldn't want to put my money down that that will happen. I hope it will and we are doing our best to make it happen, but I wouldn't want to say 'yes'."
Tavo Hellmund, the man behind the Full Throttle Productions company which is staging the race in November 2012, said Ecclestone has been tolerant throughout the situation.
"Mr Ecclestone has been incredibly patient with the challenges here in Austin," said Hellmund.
"Full Throttle Productions has worked tirelessly to bring the US Grand Prix to the city.
"It is now the responsibility of the Circuit of the Americas to make this project happen before Mr Ecclestone's patience runs out."
The dispute comes after Bahrain's Crown Prince confirmed the Gulf state will be able to hold its grand prix next season after civil unrest caused this year's race to be cancelled.
The US Grand Prix in Austin is the first of two new US races, with theGrand Prix of America in New Jersey scheduled for 2013.
PREVIOUS STATESIDE GRAND PRIX VENUES
2000-7: Indianapolis
1989-91: Phoenix, Arizona
1984: Dallas, Texas
1982-88: Detroit, Michigan
1981-82: Las Vegas, Nevada
1976-83: Long Beach, California
1961-80: Watkins Glen, New York
1960: Riverside, California
1959: Sebring, Florida
