Oct 12 (Reuters) - St. Louis Fed Bank President James Bullard said on Tuesday that he supports the Fed’s starting to taper its asset purchases next month and ending them by next spring so that the U.S. central bank could raise interest rates to tamp down on inflation if it needs to. “The story that inflation will come naturally is a reasonable one, but I only want to put 50% probability on that scenario,” Bullard said in a CNBC interview, adding that he wants to be prepared for the possibility that inflation stays high or goes higher in the months ahead. “I just want to be in position in case we have to move sooner that we are able to do so next year in the spring or summer if we had to do so.” (Reporting by Ann Saphir; Editing by Leslie Adler) Our Standards: The Thomson Reuters Trust Principles.