Complicated Home Sale

OK, two people are joint tenants on a property. a third party wants to buy the house, but it has to be with a mortgage which he can only get for a full property purchase. One of the joint tenants is opposed to the sale to the third party, but he will accept the co-tenant (who is in favor of selling to the third party) buying his half out. Does this mean that the tenant in favor of the third party has to buy out the opposed tenant in order to sell the house to the third party? If I'm correct, that would subject the favoring co-tenant to property tax, as well as the third party buying. The favoring co-tenant would like to avoid having to pay sale tax on buying the unfavoring co-tenant's half.