The first poll since the verdict showed that Robert Dole was gaining momentum in the White House race, cutting Mr Clinton's lead by four points. The gap remained a substantial 56-40 in the survey by CNN, USA Today and Gallup. But when asked about the scandal, six out of 10 polled thought Mr Clinton was still hiding something. Further damage could be caused by the forthcoming trial of two bankers charged with funnelling funds into Mr Clinton's 1990 election campaign in Arkansas.

Unlike in 1992, the issue of character seems poised to hurt Mr Clinton, especially if the courts rule that the Paula Jones sexual harassment lawsuit can go ahead. The fall of Mr Clinton's Arkansas "cronies" will feature heavily in Republican advertising, although in a shrewd move Mr Dole is staying above the fray. While his campaign aides have barely been able to suppress their glee, the official line is to maintain a lofty silence.

In a confidential memo, the Republican Party has warned all its campaign staff to keep quiet about Whitewater for the moment, the idea being to ensure that nobody steps on a story that is gathering momentum. The dirty work is being left to other Republican hard-hitters. The British-born spokesman of the House Speaker, Newt Gingrich, said the "cover-up" had "started to unravel".

Alfonse D'Amato, the Senate's main tormentor of Mr Clinton, is poised to cause upset with the public questioning of the jailed former judge David Hale. Hale was the star witness against the Whitewater couple, James McDougal and his ex-wife, Susan, and against Jim Tucker, Mr Clinton's successor as governor of Arkansas.

Mr D'Amato is calling Hale to testify at the Senate Whitewater Committee that he chairs. He has already said his final report will "raise serious questions about the conduct" of Mr Clinton and his wife, Hillary.

Hale insists that the president, when Arkansas governor, asked him to issue a $300,000 (£200,000) federally backed loan. An FBI agent testified that nearly $50,000 of the money was illegally used to pay Whitewater expenses. Mr Clinton says Hale's testimony is a barefaced lie.

Hale will be escorted to Washington from the jail where he has begun a 28-month sentence for crimes he admitted in a plea-bargain deal with the Whitewater prosecutor, Kenneth Starr.

The committee's examination of Hale could be something of a sensation as it will be carried "live" on television from a Capitol Hill hearing where no questions are barred. There are also rumblings that McDougal wants to make a deal with prosecutors to avoid a long jail term. So far he has done his utmost to distance the Clintons from any chicanery.

This article appeared in Saturday's edition of the Daily Telegraph