From some of the other articles on Biden and the mandate, apparently the mandate is the only issue on which Biden is polling above water. I guess about 58% of poll respondents actually approved of the mandate so Biden is understandably reluctant to back off what is keeping him from the teens in approval polls.
Depends on how the question is worded. When the question includes "should the government force people to vax against their will" the approval is below 50% ... for now.