Buying condo with tenants that have no lease.

[Brian Timmons]

I'm looking to purchase a condo that is roughly 20% less than the other units in the building. It currently has tenants that have not had a lease for the last three years, the seller/landlord verbally told them they have until January 31. I already get the impression they will be reluctant to leave, how should I pursue this, as I do you want the unit for my primary residence and I would like them to move out within 45 days?