Gary, it could be possible: "There is a point of contention regarding the interpretation of the Twenty-second Amendment as it relates to the Twelfth Amendment, ratified in 1804, which provides that 'no person constitutionally ineligible to the office of President shall be eligible to that of Vice President of the United States.'

While it is clear that under the Twelfth Amendment the original constitutional qualifications of age, citizenship, and residency apply to both the President and Vice President, it is unclear whether a two-term president could later serve as Vice President ... Others contend that the Twelfth Amendment concerns qualification for service, while the Twenty-second Amendment concerns qualifications for election, and thus a former two-term president is still eligible to serve as vice president. The practical applicability of this distinction has not been tested, as no former president has ever sought the vice presidency."

:)