Polk ran on a platform that embraced America 's popular commitment to territorial expansionism , often referred to as Manifest Destiny .
The convention instead settled on former Governor James K. Polk of Tennessee , who emerged as the first dark horse nominee .
Governor ran on a platform that embraced America 's popular commitment to territorial expansionism , often referred to as Manifest Destiny .
The convention instead settled on former Governor James K. Polk of Tennessee , who emerged as the first dark horse nominee .