There is an emerging consensus among financial experts and policy makers that the key to successful modifications is to reduce the amount of the borrower’s loan balance, rather than merely reducing the monthly payment. The goal is to lower the payment while restoring equity, thus giving borrowers both the means and the incentive to keep up with their payments. Administration officials have resisted that approach, in part because they believe it would be too expensive. Another obstacle is the lenders themselves. In general, a lender is unwilling to take losses by reducing principal unless the owners of the second mortgage on a home also take a hit. For banks that own the second mortgages, such losses would be huge — something they clearly would prefer not to face up to.