On Capitol Hill, Democrats called Saturday for an investigation of charges that the Bush administration threatened to fire a top Medicare official if he publicly revealed the true costs of a contested Medicare legislation. When the House passed the bill in November, the White House said the program would cost just under $400 billion over the next decade. But since then the White House has revised the estimate to be upwards of $150 billion more. It is widely assumed the Medicare bill would not have passed Congress if legislators knew program’s actual cost.