As the charge is a felony, the prosecutor has to be able to prove at a preliminary examination that there is probable cause to believe a crime has been committed and probable cause to believe that the defendant committed the crime. If there is any legal issue regarding their ability to prove probable cause or legal issues relating to the manner in which the evidence was seized, the prosecutor may be more receptive to a reduction of the charge.
If there are no issues regarding their legal proofs, then it comes down to convincing the prosecutor that the defendant is deserving of leniency. Also, it depends upon the prosecutor's office. Some prosecutor's offices have more rigid policies than others. I normally write the prosecutor handling the case to detail all of the positive attributes of my client along with any extenuating or mitigating circumstances relating to the charged offense.
An attorney experienced in dealing with the prosecutor handling the case should be able to give you an approximation of the probability for a reduction.