Aprilia MotoGP rider Aleix Espargaro described the Austin circuit as "super-dangerous" following Friday's two practice sessions, as the track's bumps caused more controversy.
The degrading asphalt at the Texan track has been a discussion point during MotoGP's previous visits, with attempts to smooth the notoriously bumpy surface with diamond-grinder trucks ahead of last year's Grand Prix of the Americas widely deemed to have failed.
Further attempts to improve matters for this year's event also appeared to have made little difference, with riders still struggling with the bumps in the first two sectors of the track in particular.
"I never rode on a track like this. It's not at the level of MotoGP, not at all," said Espargaro.
"I don't think we can race here one more year with these conditions, absolutely no way.
"Super-bumpy, especially in many corners, but more or less in the corners you can handle it.
"Corner two is disaster, but if you lose the front you are at 120, 130km/h. But in the straights, sixth gear, it's super-difficult to maintain the throttle open in one straight.
"It's very dangerous and we are [riding] one by one. I don't want to think about what's going to happen in the race. It's super-dangerous and for me this track is not at the level of MotoGP.
"The grip is not that bad, we ride at circuits with a lot less grip. But the bumps? Come on, this is not motocross. It's MotoGP, so yeah, too much.
"[On the back straight] the bike is shaking like crazy at more than 300km/h. If somebody crashes there..."
Espargaro said the only solution would be for the Circuit of the Americas to undertake a full resurfacing, although he is ensure whether his fellow riders will agree in Friday evening's Safety Commission meeting.
"It's difficult to know what other riders will think about it," he said. "For sure one or two riders will say the track is perfect, and the other 20 riders will say there's no way to race here, I'm completely sure.
"This place is fantastic, but they need to re-asphalt."
Pramac Ducati rider Jack Miller acknowledged that the bumps were "pretty bad", but defended the circuit as "one of the best on the calendar. It just needs resurfacing a little bit more" - though his team-mate Francesco Bagnaia said the track surface had become "a little bit near the limit" and was a "little bit risky".
Three-time MotoGP champion Jorge Lorenzo said Austin had become "much more bumpy, much bumpier than last year" and added: "it really needs a resurface, as soon as possible, if it is possible".
LCR Honda's Cal Crutchlow said the problem was "not necessarily bumps, they are like jumps, proper weaves in the Tarmac" and echoed other riders' complaints about the long back straight in particular.
"The straight is mad," he said.
Crutchlow said the track had worsened considerably since it was first used by MotoGP in 2013, and while he understood why the likes of Miller defended it he argued that it was now time for substantial work to improve the surface.
"I rode here in 2013 when it was like a millpond, the surface was an amazing track to ride," Crutchlow said.
"Now it is getting stupid.
"I completely agree with Jack, it adds fantastic character, some of the places where you have to manage a lot and the bike is shaking and stuff like that, it makes riding a MotoGP bike thrilling.
"But it is dangerous as well, there are no two ways about it."