just be trying to trick us. >> you don't think that we would be so silly as to not provide from time to time the capacity to throw people off, do you? >> reporter: saturday, romney launches a swing state bus tour. that could be a good time to introduce his running mate or to give those on the short list one last tryout. among those joining him along the way, ohio senator rob portman, and florida senator marco rubio, the final stage also leaves one last chance for wild speculation including an online report that president obama had said he is convinced romney will pick c.i.a. director david petraeus. >> i can say with absolute confidence that such an assertion has never been uttered by the president. >> reporter: trust us, it is not going to be petraeus. the final list seems to be down to this -- solid, safe choices of rob portman and former minnesota governor, tim pawlenty, or bolder, riskier choices of wisconsin congressman paul ryan or marco rubio.