Tough question. Look at the assignment and subletting provision in your lease. If it allows them only with the landlord's consent you are in a worse position than if it allows them only with the landlord's consent "which shall not be unreasonably withheld." In the latter case if a lawsuit was filed against you you would need to show that you had a qualified replacement and the landlord would have to show why it was reasonable to deny the assignment or sublet to the replacement. Arguments against the reasonableness of such a denial could be that the landlord is not prejudiced (harmed) by the proposed arrangement because it gives it essentially the same deal as if you'd stayed. This argument is strenthened if the lease require's you to be responsible for the tenant's performance after the transfer, in fact it could be argued that the landlord is now better off by having two "tenants" to go after if there is a noncompliance with the lease. Yes the landlord has a duty to mitigate its damages (as you do too), which means finding a new tenant, but it can take a "reasonable" time to do that. Six months doesn't sound reasonable if you have a ready replacement. The real issue is whether you're prepared to fight about it. The cost could be substantial. If the lease has an attorney fee provision and you prevail you might get a judgment against the landlord for your attorney fees. If the landlord does find a new tenant soon the problem may go away.