Although Ms. Bakara had previously emphasized that she could not speak for other Black people, she ventured to do so on this one occasion because she firmly believed that many minority people, likly most, would agree with her
D do so on this one occasion because she firmly believed that many minority people, if not most, would agree
this is an idiomatic expression - an example will be :
"solving this problem is difficult, if not impossible."
another example from 杨鹏难句: “Many critics of Family Bronte’s novel Wuthering Heights see its second part as a counterpoint that comments on,if it does not reverse,the first part,where a "romantic" reading receives more confirmation.“