WASHINGTON -- Its crunch time for Lance Bass and his bid to make history this fall as the youngest person ever to fly to space.

The 23-year-old pop singer must begin training in Moscow soon if he wants to be ready to occupy the empty third seat on a Russian Soyuz capsule bound for the international space station in October. The flight is just four months-away, meaning that if the Soyuz launches on time, Bass could not complete the recommended six-month training regimen the space station partners agreed to earlier this year.

While NASA officials have not ruled out a compressed training regimen, a spokesman for the Russian Aviation and Space Agency said it's too late for Bass to complete the required training in time for an October flight.

Rosaviakosmos spokesman Sergei Gorbunov said on Tuesday that the agency had not received application documents from Bass or his representatives.

"As far as Bass goes, the October flight is out of the question. There's only four months left and even professional cosmonauts cannot prepare for a mission in such a short time," Gorbunov said in a telephone interview in Moscow. He added that the third seat on the October flight may go to a Russian cosmonaut. However, it would most likely be used to carry additional payload to the station.

NASA, meanwhile, still appears open -- at least in theory -- to compressed training.

"The crew criteria does baseline six months but the exact amount of time required for each person would be decided on a case-by-case basis by the [Multilateral Crew Operations Panel]," said NASA spokeswoman Debra Rahn on Tuesday. "It obviously depends on a the individual and what the plans are for the mission."

Sources close to Bass acknowledge that if a deal is not concluded in the days ahead, the *NSYNC singer wont be in space anytime soon. "If it is not done this week, we are all pooched," said a source close to the Bass bid.

MirCorp President Jeffrey Manber, who has been helping Bass and his handlers at Destiny Productions navigate the Russian space bureaucracy, returned to Moscow over the weekend. Sources described this trip as a last ditch effort to get the Russians to commit to a seat for Bass. Manber did not return calls seeking comment.

At the center of the Bass bid is a big-ticket sponsorship from a deep-pocketed television network. Manber and Destiny Productions chief David Krieff are said to be very close on that front, but getting the Russian Aviation and Space Agency to commit to flying Bass has been and remains a sticking point.

"Things are very close to getting the network deal," a source said. "That could happen if in the next 36-hours, but we still need to get a seat locked up. And that has not been locked up yet."

Gorbunov said Bass could attempt to raise additional funds and undergo new tests for the following Soyuz flight in April 2003.

Meanwhile, Lori Garver, the former NASA associate administrator who has undergone a battery of medical tests and gall bladder surgery in her sponsorship-based bid to visit the space station, has since assumed the role as Bass back-up for the fall flight. Garver told SPACE.com she is hoping the Bass bid meets with great success and opens the door to more sponsorship-based space flights.