First Lady Hillary Clinton's defence of her beleaguered husband by attacking a "vast right-wing conspiracy" plotting for years to bring him down has been an effective short-term tactic. We have heard it often before when the going gets tough in the White House. But is it true? Politicians under attack often reach for conspiracy theories because they divert attention from what they are being attacked for. Supporters of the former Taoiseach, Mr Haughey, used to point fingers at British intelligence and suspect journalists when the leadership "heaves" got dangerous.

The Richard Nixon tapes now becoming available show him brooding in the evenings over the "liberals" and the "Jews" out to get him. Mrs Clinton herself as a young lawyer served the Congressional committee which investigated Water gate, often using revelations from the Washington Post. Mr Nixon and his allies would have seen her as part of a "left-wing conspiracy" plotting his downfall.

Mrs Clinton, however, can line up an array of conservative enemies who want to drag her husband down. There is the video by tele evangelist, the Rev Jerry Falwell, called The Clinton Chronicles, in which the President is accused of treason, murder and a lot else.

A former Washington correspondent of the London Sunday Telegraph, Mr Ambrose Evans-Pritchard, recently wrote a book called The Secret Life of Bill Clinton which is littered with dead bodies from murky goings-on in Arkansas. The suicide while working at the White House of Vince Foster, former close friend and legal counsel of the Clintons, is also seen by the conspiracy theorists as highly suspicious.

The New York literary agent, Ms Lucianne Goldberg, the woman who advised Linda Tripp to tape Monica Lewinsky's allegations about her affair with the President, was once used as part of a Nixon "dirty tricks" campaign against a Democratic contender, George McGovern. She also encouraged Ms Tripp to write a book about "inside the Clinton White House".

The Whitewater independent counsel, Mr Kenneth Starr, has been described by Mrs Clinton as a "politically-motivated prosecutor, who is allied with right-wing opponents of my husband". She complained bitterly about how Mr Starr is making both their lives a misery as he has spent more than four years "looking at every telephone call we've made, every cheque we've ever written, scratching for dirt . . .".

The Clinton White House has compiled a 331-page report in an attempt to prove the conspiracy theory. Quoting from hundreds of news clippings, the report claims there was a "conspiracy commerce" which began in ultra-conservative and right-wing fringe publications in the US, made its way across the Atlantic to the British tabloids and conservative newspapers like the Sunday Telegraph and then back to the US to be picked up by the right-wing radio talk shows, the Murdoch-owned New York Post and conservative publications such as the Wall Street Journal Opinion page, the Moonie-owned Washington Times and the American Spectator.

This last publication, which broke the Paula Jones story four years ago, has been subsidised by foundations controlled by Richard Scaife Mellon, the Pittsburgh heir to the Mellon family fortunes.

So there is plenty of material if you want to believe like Mrs Clinton that "malicious and evil-minded" political opponents are "trying to undo the results of two elections".

The trouble with the theory is that much of the journalism exposing Democratic fund-raising abuses as well as Monica Lewinsky's alleged involvement with the President is coming from what would be regarded as "liberal" media which would have given editorial support to Mr Clinton in his two election campaigns. These include the Washington Post, the New York Times and Newsweek.

Ms Lewinsky and her mother are Democratic supporters and contributors. A close family friend who helped Ms Lewinsky secure her intern job in the White House is the New York Democrat, Mr Walter Kaye, who contributed $300,000 (£214,000) to the party.

The unpalatable fact is that Mr Clinton has an unsavoury past as regards philandering, and this leaves him continually vulnerable to "bimbo eruptions" as his Arkansas chief-of-staff, Betsy Wright, memorably termed them. Now there is evidence, not yet proved, that he has an unsavoury present or recent past concerning actions under the White House roof.

You don't need conspiracy theories to see how this spells danger for a President who continually preaches "family values". However, Mr Starr and his Whitewater investigation in long-ago property schemes sit oddly with allegations of hankypanky in the White House; but a complicated link does exist in the person of Vernon Jordan. He is the close Clinton confidant who secured a job for Ms Lewinsky with Revlon (since withdrawn) when the President sent her to him.

Mr Starr, who has dismissed Mrs Clinton's "conspiracy" charge against him as "nonsense", has come under scrutiny for his own conservative and Republican background. He was once considered by a conservative women's group to write a legal brief opposing the President's claim of immunity while in office from Paula Jones's sexual harassment case.

He is also a long-time friend of Alfred Regnery, whose firm has published a number of books highly critical of Mr Clinton, including one by a former White House FBI agent, Gary Aldrich. In his book Unlimited Access Mr Aldrich described chaotic scenes in the early Clinton White House where he had to investigate young Democrat activists for drug use, but he was discredited for claiming that the President was smuggled out of the White House for trysts in Washington hotels.

However, Mr Starr, whatever his background and his friendships, has to deal with rules of evidence and strict legal constraints in his enquiry. If he is to indict Mr Clinton for perjury or suborning Ms Lewinsky to commit perjury it will have to be on the basis of witnesses a grand jury will find credible, and not on the basis of newspaper articles or radio talk-show hosts like G. Gordon Liddy (who has boasted of using pictures of the Clintons for target practice).

Mrs Clinton has rightly pointed out that there has been a media "feeding frenzy" since the Lewinsky allegations broke last week and that now a strict legal process has to work itself out. "Take a deep breath," she advises. This is going to go on for a long time.

Meanwhile she encourages journalists or anybody to go after "the great story here for anybody willing to find it and write about it and explain it . . . this vast right-wing conspiracy that has been conspiring against my husband".

She can also be sure that there is a small army out there, not all right-wing conspirators, trying to show that his own recklessness, not ideology, will cause his downfall.