Can you sublease it? Yes and no. You can try to get away with it, but it is likely a breach of the lease based upon what you posted. If the landlord finds out about it and wants to enforce the terms of the lease, you will be named as a defendant in a lawsuit for possession and money damages.
You are on the hook no matter what (the sublease would not relieve you of liability). I am NOT suggesting that you do anything that would breach the lease. But if you try to get away with it, you expose yourself to a claim for rent, possession, attorneys' fees, and court costs. Another thing to consider is what happens if the subtenant does not vacate (and the landlord insisted upon possession at the end of July) - you will STILL be on the hook for that time period and may have exposure to additional claims for landlord's damages due to his inability to rent to an incoming tenant.
Do you think this landlord would discuss a lease assignment to the current subtenant/occupant? Again, I am NOT suggesting that you do that (because then the landlord is on notice as to what you are doing or thinking of doing). But you can consider whether or not to approach the landlord and work something out.
Remember - it is YOUR obligation to remove the subtenant by the end of July unless a new agreement is made between the landlord and that subtenant (in which case you want to make sure you get a written release).
DISCLAIMER: The information you obtain at this site is not, and is not intended to be, legal advice. You should consult an attorney for advice regarding your individual situation. While I invite you to contact me and welcome your calls, letters, and electronic mail, contacting me does not create an attorney-client relationship. Please do not send any confidential information to me until such time as an attorney-client relationship has been established (as by signing a written legal services agreement or by entering an appearance in court on your behalf). Any response is intended solely to give you limited, general information on the issue presented. Michael J. Carmody is licensed to practice law in Virginia, the District of Columbia, Maryland, and Tennessee.