Red Bull team principal Christian Horner says he "certainly wouldn't vote in favour" of the Halo at present as he calls for more research on cockpit development.
An updated version of the Halo was tested by Ferrari during Friday practice at Silverstone, but Sebastian Vettel declared himself unhappy with the impact it had on visibility. The FIA is keen to introduce increased head protection in 2017, and has warned teams to expect the Halo to be approved, promising a final decision by the end of July.
Horner - who was speaking after the British Grand Prix but before Pierre Gasly tested the Halo on his Red Bull at the start of testing at Silverstone on Tuesday - says more work is needed before approving such a device.
"Personally I am not a big fan of the Halo," Horner said. "I think it is an inelegant solution to the problem that it is trying to deal with.
"I’d prefer there to be more research time taken to do the job properly, rather than rushing something through that may have other consequences. So, I am not a big fan of the Halo and the limitations that it has.
"I certainly wouldn’t vote in favour of it at the moment."
Horner would get the opportunity to vote on the Halo's introduction on Strategy Group level as the technical regulation change would need approving by F1's key stakeholders.
Red Bull has been developing an alternative to the Halo known as the Aeroscreen, which it debuted in practice in Russia earlier this season. However, the team has stopped investing in the device with the FIA identifying the Halo as the more ready solution for 2017.