Bashshar and Iran

I am told by a knowledgeable source that at one point when the Syrian rebels advanced toward Damascus, Bashshar expressed a willingness to step down but that the Iranian regime did not let him and pressured Hizbullah to intervene on his behalf.  I don't know if this is true because the impression that I have is that Bashshar is very stubborn and does not seem to be the type who would step down voluntarily.  But who knows?