Should that deadline pass, however, the IOC would open up bidding to other interested parties, said Karl Stoss, who heads the IOC's Future Host Commission for the Olympic Winter Games.
The Swiss project is currently the only bid in talks with the IOC as part of its privileged dialogue. The last time the winter sports powerhouse hosted the Winter Olympics was back in 1948 at St. Moritz.
"The IOC is only negotiating with Switzerland. This period was put in place to allow for the Swiss public and political consultation processes, which are fully respected by the IOC," Stoss told an IOC session two days before the start of the Milano Cortina Winter Olympics.
"Unless this is completed by 2027, the IOC will have to open up the 2038 Winter Games to other interested parties," he said.
Switzerland, which hosts the IOC's headquarters in Lausanne, has repeatedly rejected Olympic plans in recent years, with projects from Sion, Graubunden and St Moritz/Davos failing to gain much local support.
Many other Olympic bids in the German Alps and Austrian Alps, including Innsbruck 2026, suffered a similar fate in recent years.
Alpine populations are concerned that the Winter Games, with the construction and human activity plus tens of thousands of visitors for the competition, would be an environmental burden for the fragile ecosystem of these mountains.
Stoss said the Swiss parliament was expected to vote on committing financial support to the project in December 2026.
"If all requirements have been met by then the IOC could potentially open up a targeted dialogue in December 2026, with ... a potential host election in April 2027," Stoss said.
France will host the 2030 Winter Olympics in their part of the Alps and the 2034 Games will be held by the US in Salt Lake City.