Canvasing or Canvassing: How To spell?
The word Canvasing is misspelled against Canvassing, which is present continuous of "Canvass"
Canvassing has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings canva & ing which should not be misspelled with single 'S'
Wrong Spelling:  canva-s-ing  Correct Spelling:  canva-ss-ing 
Find more wrongly spelled words of Canvassing to spell it well.