ELECT Bill Clinton, the candidate was wont to say during the 1992 campaign, 'and you get two for the price of one'. But that was back in the good old days, when Hillary Clinton was an asset beyond argument. She remained one until a week or so ago when that Arkansas imbroglio called Whitewater became the only topic in town.

To the chagrin of Republicans, Whitewater almost certainly is not Watergate. But right now it offers a passable imitation. A top White House aide has been forced to resign, subpoenas and accusations of a cover-up are flying in all directions. For theatrics though, nothing has matched Bill Clinton's passionate defence of his wife: 'Never have I known a person with a stronger sense of right and wrong in my life - ever.' Those words were brave, even moving. But they were also self-interested. At that moment, Bill Clinton was defending not only his wife, but his presidency.

The Clinton White House is like no White House in history. Never has a First Lady, not even Eleanor Roosevelt, been as powerful. None has been entrusted with an issue like health- care reform, potentially the most important piece of social legislation here for three decades. No first lady has ever been sent to Capitol Hill to present so vital a programme, and carried off the feat so dazzlingly. None has been as influential in high-level appointments. Privately, any White House official will testify to her authority. Irrespective of the alleged philandering by her husband, the Clinton marriage has always been in good measure a professional partnership of equals. By their staff she is feared at least as much as he, and understandably so.

Download the new Independent Premium app Sharing the full story, not just the headlines

By any yardstick Hillary Clinton is a remarkable woman, a role model for every working mother in America, and a lawyer whose talents would have made her a leading candidate for Attorney General in a Democratic administration headed by anyone other than her husband. In the Yale Law School class where they met in 1971, she passed out first. The future president only came fifth. In the Clinton household she was the main breadwinner. By the time she left the Rose law firm in Little Rock, she was making more than dollars 200,000 a year, chicken feed by the standard of hot-shot big city lawyers, but six times more than the paltry dollars 35,000 salary of an Arkansas governor.

The problem is that where First Ladies are concerned, there are no guidelines. The Constitution does not mention the job. Her name does not appear on the presidential ballot paper. She is not confirmed by a Senate committee. In a system founded upon the principle of accountability, she is all but unaccountable. Normally this would not matter; Jackie Kennedy, Barbara Bush - even the redoubtable Nancy Reagan - did not pretend to high policy-making. Hillary does. A formal press conference or two might help; but then again, they might not. Only too aware that going solo would reinforce the perception that it is she who calls the shots at the White House, Mrs Clinton gives almost no interviews of substance. Those she does give are mostly to gossip columnists and women's magazines, with strict ground rules laid down in advance.

Most important of all, she cannot be sacked. Nothing less than divorce will remove a First Lady from the White House. In these circumstances, Hillary Clinton must perforce be treated as an extension of her husband's juridical and official person - in other words, part of the Clinton package. That, after all, was how Bill Clinton sold himself to America. And in the case of Whitewater, that is precisely what has happened.

Only the Almighty, and perhaps not even He, knows the truth about Whitewater. But the questions about Hillary's role boil down to three. Did she cut tax corners in the Whitewater real estate venture the Clintons set up with their friends, Jim and Susan McDougal? As a partner at the Rose law firm, was she involved in improper conflicts of interest when she worked on the cases of Madison Guaranty, the failed savings and loan company run by McDougal, and of Dan Lasater, a dubious banker who was also a family friend of the Governor and his wife? And last, and most readily comprehensible, has she since 1992 ordered any of the Whitewater documents to be shredded?

None of these questions has been answered. What can be said with certainty is that she, far more vigorously than her husband, resisted the appointment of a special counsel to investigate Whitewater. At every stage, from the removal of documents from the office of the late Vince Foster last July to the secret meetings between White House and Treasury officials to discuss the federal investigation into Madison, 'Hillary's people' were involved - most notably her own chief of staff, Maggie Williams, and the outgoing White House counsel, Bernard Nussbaum.

But why them? And did the Clintons know about those meetings, or even organise them? In fact, whether it was Bill or Hillary who knew is immaterial. Again, for lack of a defined role, the First Lady's behaviour must be treated as that of her spouse. Suppose Bill Clinton were to be indicted for some crime arising out of Whitewater. Plainly, he would have to resign. But were Hillary to be indicted and not he, it is equally inconceivable that he would also not be forced out.

The above is fantasy. What is not fantasy are the practical effects of what some call 'Hillary-gate'. She herself is said to be upset but unbowed. In an interview with Elle magazine to appear next month, she defiantly calls Whitewater 'a well-financed, well-organized attempt to undermine my husband and, by extension, myself . . . I know nothing bad happened'. But her public appearances have been reduced, and for her floundering health-care scheme Whitewater could be the last straw.

From the moment she dazzled Capitol Hill last autumn ('In future the President will be known as your husband,' Dan Rostenkowski, who chairs the House Ways and Means Committee, gushed at one appearance) Hillary has been her plan's most potent weapon. No longer. In Washington more than anywhere, vulnerability equals weakness. Today Hillary Clinton is vulnerable; so, therefore, is Bill Clinton. 'Two for the price of one' has turned from blessing into curse.

(Photograph omitted)