"He could of won if he'd only tried a little harder." Wrong. It's a confusion of sound. "Could've" sounds like "could of." It's "could have" (or "could've"), not "could of."
"He could've won."
A Practical, Random Guide for Writing and Communicating Well
"He could of won if he'd only tried a little harder." Wrong. It's a confusion of sound. "Could've" sounds like "could of." It's "could have" (or "could've"), not "could of."
"He could've won."