And while the Bush administration is leaving it to the next president to decide how the mortgage finance companies will operate further out, the actions taken by their conservators now will have an immediate influence on the cost to taxpayers - and to the economy - of stabilizing the nation's fragile housing market. Regulators are walking a fine line between protecting the government from losses and helping struggling homeowners and the broader economy, according to financial and political analysts. If officials modify too many home loans or the companies suffer high defaults on modified loans, taxpayers will be stuck with an inflated bill.