WASHINGTON - Federal Reserve Chairman Ben S. Bernanke faced an unusual political trial yesterday and disputed accusations that he pressured Bank of America Corp. to acquire Merrill Lynch & Co. Inc. in a deal that cost taxpayers $20 billion.

WASHINGTON - Federal Reserve Chairman Ben S. Bernanke faced an unusual political trial yesterday and disputed accusations that he pressured Bank of America Corp. to acquire Merrill Lynch & Co. Inc. in a deal that cost taxpayers $20 billion.