Last week, an obscure government actuary named Richard S. Foster rocked Washington with accusations that the Bush administration had muzzled his economic forecasts for overhauling Medicare. Mr. Foster calculated that it would cost more than $500 billion to provide a prescription drug benefit over the next 10 years, but says his boss threatened to fire him if he shared the information with Congress. Lawmakers passed the bill relying on a much lower -- and politically palatable -- figure of $400 billion.

The health and human services secretary, Tommy G. Thompson, immediately ordered an internal investigation, while Mr. Foster's boss, who has since left government to become a health industry lobbyist, denied making any threats. But Democrats wasted no time in charging that the White House had tampered with the truth.

The Foster case was only the latest in a string of high-profile controversies over how the Bush White House handles information, from scientific data to health facts to intelligence in the war in Iraq.

In recent weeks, Environmental Protection Agency employees have said they were told to forgo the customary scientific and economic studies in developing a rule on mercury emissions. Nobel laureates issued a statement asserting the administration had distorted scientific fact on the environment, health, biomedical research and nuclear weaponry. Mr. Thompson acknowledged his agency had altered a report on racial disparities in health to sound more positive. And the Carnegie Endowment for International Peace, a nonpartisan research institution, found that administration officials"systematically misrepresented" the threat from Iraq's nuclear, chemical and biological weapons programs...

...But the line between spin and deception is a thin one indeed, as Mr. Clinton ("I did not have sex with that woman") amply demonstrated. And as the Medicare controversy unfolded last week, Republicans noted pointedly that President Bush won election by vowing to restore integrity to the White House, a goal they say he has more than achieved...

...So the question is not whether the Bush administration has shaded the facts, but whether in doing so, it has approached a tipping point, beyond which even its Republican allies in Congress no longer trust what it says.

"I think the White House has come under such disrepute over the years that whether we have approached what would be the tipping point is hard to say," said James MacGregor Burns, a presidential historian at the University of Richmond, who studies leadership."A lot of the cynicism among the public results from failures on the part of not only this president, but also earlier presidents, in putting out full and accurate information."

With its agencies and research institutions churning out analyses, Washington is awash in facts and figures. Alice Rivlin, who has served Democratic presidents from Johnson to Clinton, said Americans have been"very lucky as a nation" to have career bureaucrats dedicated to producing accurate information."What has characterized our government, over all the time I've been in it, is that the numbers are honest," she said...

In 1981, David A. Stockman, who ran the Office of Management and Budget under President Reagan, nearly lost his job after he confessed to a magazine reporter that upon discovering that the White House could not simultaneously reduce taxes, increase military spending and cut the deficit, he altered his computer models to suggest that it could.

"This thing pales in comparison to what David Stockman did," said Lou Cannon, a biographer of President Reagan, referring to the Medicare controversy. Of the Bush administration, he said,"If you invented some deceptiveness scale, I don't think this administration stands out."

Others, though, say the Bush administration bends the facts more than most.

"I think the Bush administration, for various reasons, seems to have a higher ratio of statistical prevarication than most," said Kevin Phillips, the author of"American Dynasty: Aristocracy, Fortune and the Politics of Deceit in the House of Bush," a book that is highly critical of the president.

One reason may be the ballooning deficit, which Mr. Phillips said is forcing the White House to put a positive spin on its economic numbers -- especially in an election year. The deficit was clearly an issue with the Medicare bill. With conservative Republicans balking at the $400 billion cost, it might have been defeated, or significantly altered, had Mr. Foster's estimates been widely known.

While Democrats on Capitol Hill are trying to evoke memories of Watergate ("What did the president know; when did he know it?" Senator Edward M. Kennedy of Massachusetts asked last week about the Medicare numbers), Mr. Cannon, the Reagan biographer, says it is difficult to imagine the president paying attention to the work of a lowly actuary. Questions about Mr. Bush's credibility, he said, will ultimately be decided on the far bigger issue of how the administration handled intelligence information leading up to the Iraq war.

Mr. Burns, the presidential historian, agrees."If you make a mistake or a misstatement about domestic policy, you can retrieve it, but if you make a mistake in military policy of the sort that involves bad information, there may be no remedy," he said."That, it seems to me, is the tipping point."...