You would not typically have any leverage to negotiate unless the employer is engaging in some type of wrongful conduct against you, such as prohibited discrimination, retaliation, or breach of contract.
Without that, the best you can do is ask the employer for additional time typically unless their policy sets out a procedure for negotiating additional time.
I hope you found my answer helpful; please click on the GREEN ACCEPT button above for my answer. This is necessary for me to be paid for my work and so that I can get credit for assisting you. Your question will not close, and you will still have the opportunity to follow-up if needed. Leaving a bonus and positive feedback is not required, but doing so is certainly appreciated!
If you have additional questions, please keep in mind that I do not know what you already know or don't know, or with what you need help, unless you tell me. Please consider that I am answering the question or question that is posed in your posting based upon my reading of your post and sometimes misunderstandings can occur. If I did not answer the question you thought you were asking, please respond with the specific question you wanted answered.
Also remember, sometimes the law does not support what we want it to support, but that is not the fault of the person answering the question, so please be courteous. Thank you.