Hi.
If there is no offer from interested party on paper…I would be inclined to take the tenant.
You are in a position where you need the rent to help cover the costs…in the worst case scenario you may have to hold the property longer until close to the end of the lease, then advertise say at the 10 month mark of the 12 month lease. You then have the option of advertising it as with or without tenant. The property may also be worth more in 12 months time.
This will at least help with the finance burden!

cheers