Not His Fault

The possuk (4:3) says about the כהן המשיח that his sin is אשמת העם.  What does this mean, what does his sin have to do with everyone else?  There are different explanations in the meforshim.  Rashi brings both a halachik perspective that he is only obligated on a  בהעלם דבר עם שגגת מעשה and an aggadah that his sin is the fault of the people, for they are dependent on him to atone for them and pray for them and he has become impaired. The Rashbam says that if a leader sins then people will follow his lead and they will sin as well.  The Sforno has the opposite take of the Rashbam.  He explains that sometimes the leader's faults are really just a reflection of the sins of the people.  He adds that's why the possuk never says regarding the משיח the word ואשם for he doesn't require teshuva for its not his fault that he sinned; it was because of the people.  Not sure what does the Sforno mean, how could the people cause the leader to sin?  And why does the leader bear no responsibility to the extent that he says there is no need for teshuva?  However, we do see from the Sforno that if a leader errs it may not be because of faulty leadership but rather the leader is merely a reflection of the mistakes of those that he's leading. (Even his own private sin as this parsha is dealing with, not only a leadership error.)