Haas Formula 1 team boss Gunther Steiner has explained the "close call" of forgoing an offer to Nico Hulkenberg in favour of retaining Romain Grosjean for 2020.
Hulkenberg will be released by Renault at the end of the season, with current Mercedes reserve driver Esteban Ocon - who was due to drive for Renault this season, before the deal fell through - taking his place alongside Daniel Ricciardo.
Haas had been interested in securing Hulkenberg's services for the '20 campaign to partner Kevin Magnussen, before announcing on the eve of the Singapore Grand Prix that it had opted to field an unchanged line-up instead.
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Commenting on the prospect of Hulkenberg joining Haas, Steiner admits signing him was a "close call", but felt retaining Grosjean was more sensible as "the car this year is not performing as we want" and a line-up change could prove detrimental in car development.
"It was a close call, because they are both very good drivers and I hope Nico stays in F1," Steiner explained.
"I like him and he's a good driver. But in the end we decided to stay with Romain.
"He is with the team for four years, we know his highs and his lows. We know on a good day he's a very good driver. He knows the team very well.
"The biggest reason is our car this year is not performing as we want it to perform - which in the end has nothing to do with the drivers we've got at the moment.
"It's the car, we're very conscious about that.
"Changing the driver now, I don't know if it would help us make the car better. It could, but it also could not, because the new guy wouldn't know where we start off.
"Romain was a big part of getting the understanding of why we are wrong with the car at the moment. He was a big help. And we didn't want to have any more unknowns or risks."
Asked by Autosport whether there were other factors that went against Hulkenberg besides driver continuity, Steiner said: "The main thing was that one.
"Do we want to make this step and introduce a new element to the team? That was the main reason why we stayed with Romain, because we know what we've got."
Steiner, who said he and team owner Gene Haas were "very aligned" on the decision, denied suggestions that the two drivers' respective salaries played a part, as he believes Hulkenberg could've been available on an "acceptable" deal.
He made it clear, however, that Hulkenberg had not been approached with any formal offer.
"In the end, I want to clarify that - we decided to take Romain but I don't know if Nico would've come.
"We spoke but we never made a formal offer. So I don't know if he would've accepted or not, that you need to ask him."