Honda F1 chief Yusuke Hasegawa has conceded that the Japanese manufacturer are struggling to convince McLaren but are doing everything they can to keep the partnership alive.
McLaren are set to make an announcement this week and clarify their engine situation for next season.
They are expected to divorce Honda and strike a new deal with Renault, but Honda are not giving up the fight just yet.
"I'm still trying to make good performance to convince them but I'm not sure it will be enough," Hasegawa said
"Honda never give up on keeping this collaboration."
Hasegawa believes Honda have made gains and that the high-pressure environment they are working in has enabled them to make big strides forward.
"It accelerated our development," he added. "It becomes motivational inside the factory.
"Since Austria, the spec 3 engine introduction, our development has accelerated and the rate of development is very good.
"We saw some performance gain with each upgrade so it's very encouraging."
Hasegawa is also confident of a strong result at Singapore, a street circuit expected to suit, but ruled out any major engine updates.
"We have some confidence about competitiveness [at Singapore]," Hasegawa said.
"We have already decided the current engine will go to Singapore.
"We may update some settings or engine settings but we cannot do a big update in Singapore."