New York ? The field of possible buyers for Lehman Brothers narrowed Saturday, but the parties involved in the discussions over the wounded investment bank’s future were at loggerheads over how to finance the rescue.

An investment banking official said Bank of America Corp. and Britain’s Barclays Plc have emerged as the front runners for Lehman Brothers after a possible cash injection from its rival Wall Street banks and brokerages.

Top officials from the Federal Reserve and the Treasury Department and executives from several Wall Street banks met at the New York Fed’s downtown Manhattan headquarters Saturday for the second day in a row try to hash out a deal to rescue Lehman Brothers.

The financial world was watching. Failure could prompt skittish investors to unload shares of financial companies, a contagion that might affect stock markets at home and abroad when they reopen Monday.

Discussions are expected to continue today, said Andrew Williams, a spokesman for the New York Fed.

The investment banking official, who asked not to be named because the talks were ongoing, said the investment houses were balking at paying to polish up Lehman’s balance sheet so Bank of America or Barclays could buy a financially clean firm.

He said the investment banks were angling for the government to provide some money, as it did when it helped JPMorgan Chase & Co. buy Bear Stearns in March, because they would get little to nothing in return for their help.

The government has drawn a line in the sand over using taxpayer money to help rescue Lehman Brothers, however.

The official said the talks were tense and neither side appeared willing to back down.

Besides selling the company whole or piecemeal, Lehman could be liquidated, perhaps with financial firms agreeing to still do business with the company as it wound down.

Or, a financial company or companies could buy Lehman’s “good” assets. Its shunned or devalued real-estate assets could be placed in a “bad bank” financed by other banks.