The vote is scheduled even though Christie and the state Assembly's prime sponsor of medical marijuana struck a deal on regulations last week.
The vote could still be put off.
Activists are upset that Christie has proposed capping the potency of marijuana that could be sold to patients with certain conditions.
Thirteen other states allow medicinal cannabis and none of them have a similar provision.
Some lawmakers say the rules should be struck down because the law they passed to allow pot for patients didn't have the restrictions.