The branching ratio of the rare decay K+=>pi+,nu,nubar is sensitive to
most new physics models that extend the Standard Model and solve its
considerable problems. As the SM prediction for the branching ratio is theoretically
robust at the 5% level, a measurement with comparable precision offers unique
discovery potential for new physics. The proposed experiment P996 at Fermilab
extends the successful program of Brookhaven experiments E787 and E949 that
observed the rare decay using a stopped kaon beam. Coupled with a
high-duty-factor beam provided by operation of Tevatron as a "Stretcher", P996
would be capable of a precision measurement the K+=>pi+,nu,nubar branching
ratio.