Red Bull owner Dietrich Mateschitz says the energy drinks giant will walk away from Formula 1 unless it has a competitive team – which includes its engine supplier.
After four consecutive drivers' and constructors' championships from 2010 to 2013, Red Bull lost out to Mercedes last year as the German manufacturer's power unit proved to be a step above the opposition.
Red Bull has been critical of Renault's engine after a poor start to 2015, in which the Milton Keynes team can count a lapped sixth place in Australia as its best result.
Red Bull team boss Christian Horner had called for equalisation rules to stop Mercedes' dominance, while the company's advisor Helmut Marko has stated the energy drinks company would stay in F1 as long as it made sense financially.
"It's not to say we'll continue forever"
On Thursday, Mateschitz said Red Bull would re-evaluate its commitment to Formula 1 if it continues to struggle to match Mercedes.
"We will only stay in Formula 1 if we have a competitive team, and we need a competitive power unit for that," Mateschitz was quoted as saying by the Austria Press agency.
"If we don't have one, we can race with the best car and the best drivers and still have no chance of competing for victory.
"We are not a car manufacturer who could justify the investment. So we rely on Renault to close the gap to Ferrari and, above all, Mercedes.
"If the cost-benefit calculation isn't right anymore, it's not to say that we'll continue forever."
More pressure on engine supplier
The Austrian said that Renault's competitiveness – or the lack of it – would be a big factor in making a decision about the future.
Mateschitz suggested the French manufacturer could also pull out of F1 if it finds it cannot be strong enough to fight at the top.
"Of course Renault can also weigh its options, including pulling out," Mateschitz added.
"As a manufacturer, it's your task to deliver a competitive power unit. If you can do that, it's great. If, for whatever reason, you can't do that, you should pull out.
"Then the consequences for us would be clear, too."