The Haas Formula One team have decided to retain Romain Grosjean for 2020 rather than opt for Nico Hulkenberg because the Frenchman was a known quantity, team boss Guenther Steiner says.

The US-owned team will now have an unchanged lineup of Grosjean and Danish driver Kevin Magnussen for the fourth year in a row.

Magnussen, 26, already had a contract for 2020 while 33-year-old Grosjean had faced an uncertain future after costly mistakes.

“We know what we have got and we can work with that,” Steiner told reporters at the Singapore Grand Prix on Thursday.

“That’s why we took the decision to stay with Romain for another year.”

Haas, who joined the grid in 2016 and have a close technical partnership with Ferrari, are enduring their worst season. They are ninth out of 10 in the constructors’ standings with only Williams below them and seven races remaining.

Fifth in the standings last year, they have struggled to extract speed from their cars in the races and to get the tyres performing.

Steiner said changing drivers while the team were trying to sort through their problems would only introduce further unknowns.

“It is the car, we are open about that, conscious about that,” he said.

“And now changing driver, I don’t know if it would help us to make the car better. The new guy wouldn’t know where we start off.”

Hulkenberg, 32, is set to be replaced at Renault by young Frenchman Esteban Ocon alongside Australian Daniel Ricciardo.

Haas had looked his best chance of staying on the grid, despite having a difficult relationship with Magnussen following track clashes between the two, for a 10th season.

Steiner said the team had held talks with the German but they had not progressed to the point of a formal offer.

Six of the 10 teams now have confirmed lineups, with Alfa Romeo and Williams yet to confirm their plans. Red Bull have a selection of their own drivers to choose from for their two teams.