Formula 1 teams will meet on race morning at the British Grand Prix to try and reach agreement on a move to ditch the ban on the off-throttle use of blown diffusers, with outfits not yet unanimous in their support of the matter.
After controversy over the Silverstone weekend about the FIA's imposition of its ban on blown diffuser use under braking, the governing body offered on Saturday night to allow teams to keep the systems if there was unanimous support among them.
Although leading outfits including Red Bull Racing, Ferrari, and McLaren are understood to be in favour of the move, other teams are not totally convinced.
Williams, who was the original catalyst for the blown diffuser clampdown after querying potential future designs with the FIA, said it would wait until after it has discussed matters with engine partners Cosworth before deciding if it supports the move.
When asked about his expectations for the Sunday morning meeting, Williams technical director Sam Michael said: "I don't know yet. I think the main thing is that we had a meeting this morning and it became pretty clear that Williams, Ferrari and Sauber were not fully aware of what all the issues were with Mercedes and Renault.
"And though those teams felt there had been a lot of dialogue about how they needed to re-tune their engines for different throttle and fuel - we didn't know anything about it.
"The first time I heard there was going to be a different throttle position was from a journo at lunchtime yesterday. So I think during that meeting, I came out of there with a lot better picture of what their actual problem was, because unless you sit and look at things in detail it's a bit difficult.
"But during that meeting I had Paddy Lowe explain Mercedes position and Adrian Newey explain Renault's position, and then I had a further quite detailed conversation with Adrian about what Renault's issues were. And now we have a much better view of what their actual issues are. How that is going to affect tomorrow I don't know yet."
Michael added that he was undecided yet on which way he would vote in the meeting.
"I've heard all the arguments and now I need to sit down with Cosworth and our guys to see what our position is," he said. "Really, that's just our view as well, it doesn't mean that's what the FIA will adopt."
McLaren team principal Martin Whitmarsh said he feared that the rest of the season could be blighted by 'paranoia' if individual teams stood up and blocked the efforts to get rid of the ban.
"Inevitably in F1 self interest sometimes prevails, but I think unless we go back to that, then this season is going to be fraught with paranoia, the feeling of being hard done to, being disadvantaged," Whitmarsh explained. "We have got what we have got.
"It may be worse for other teams. It has certainly hit this team, it has hit the performance of our car, and I think that is evident from the stop watch - and hopefully from our perspective we get to a situation.
"It is not good to change the rules midway through the year. If you do that, the team that has worked hardest to perhaps refine that particular rule may well be disadvantaged."
Whitmarsh believes that going back to the regulations as they were in Valencia was undoubtedly the best solution for everybody.
"This morning it seemed it was likely to happen," he said when asked how confident he was that unanimity could be found. "Whether people like exhaust blowing or not, it is probably the most equitable situation.
"We had a free market so to speak leading up to Valencia. People in good faith expect that is what we have got, that is what we will develop our engines for, that is what we will develop our exhaust for, that is what we will develop the fundamental aerodynamics of the car and the vehicle handling and set-up, so everything we have done is based upon that, and working in good faith.
"No one was complaining about it 18 months or 12 months ago or 6 months ago, so I think it would be the fairest thing."
Mercedes GP team principal Ross Brawn was less optimistic, however, admitting that several teams were not too keen for the ban to be overturned.
"Difficult," he said. "We are meeting at 10:30 tomorrow. It was clear from the meeting that we had today that there were different opinions. It was held in a constructive fashion, but there were different opinions and some of the teams went away to consider their opinions.
"In fairness, Red Bull, Ferrari, McLaren, ourselves were happy to try and find a solution that we felt was good for Formula 1. It was the first time that some of the teams had heard the proposal and they want to reflect on it and give an answer tomorrow. I hope that we find a solution because we want to tidy this thing away and get on with the racing. I really don't know where we will be tomorrow, but I hope that we do find a solution."
Brawn hopes that those teams who felt they would be disadvantaged by the ban not taking place would be open to considering the ultimate benefits for F1.
"If we go back to that [Valencia specification], we will still have some teams that are unhappy with that situation. It's a question of whether they can recognise that it's not easy to find a solution.
"Whichever way we go, someone will feel aggrieved about the solutions that take place. Most people now recognise that it might have been best left to the end of the year and then move the exhausts to a new position next season where they will be more benign and we could have avoided these difficulties."
If agreement is not reached at the TWG meeting, Brawn reckons that the FIA would stick with the regulations as they were in place at Silverstone.
"Where we were today is what the FIA have decreed and are comfortable with," he said. "So I imagine we stay where we are."