Porsche has revealed that it will decide its future in the LMP1 division of the World Endurance Championship before the end of this month.
The admission comes against a backdrop of rumour that Porsche is gearing up to end its involvement in P1 after the 2017 season.
Porsche LMP1 team principal Andreas Seidl said: "We will make the decision before the end of July."
He refused to elaborate on the comment, saying he was focusing on this weekend's fourth round of the WEC at the Nurburgring.
Porsche is in theory committed to racing on in LMP1 until the end of the 2018 season after extending its initial three-year race programme covering 2014-16 in August 2015.
Speculation about a pull-out has been fuelled by the presence of senior Porsche figures at the Formula E races in Monaco and Berlin.
Toyota said it was unclear what a Porsche withdrawal would mean for its plans, which include a firm commitment to the WEC until the end of 2019.
"At the moment, with the situation we know, our management has committed to next year," said Toyota Motorsport GmbH technical director Pascal Vasselon.
The disappearance of Porsche in the wake of Audi's withdrawal at the end of 2016 "would be a problem", he admitted.
"We will rethink our strategy when the conditions change: I cannot elaborate more on something that has not materialised," he said.
"What our position would be, I do not know, but sure we need competitors."
Vasselon said that he was hopeful that new manufacturers would enter the P1 arena when new regulations for 2020, which were announced during the week of the Le Mans 24 Hours last month, come into force.