The pre-emptive onslaught coincided with publication by the Conservative Research Department of dossiers of selective quotations from Mr Smith, Margaret Beckett, his expected deputy, and John Prescott, the outside challenger for the deputy's post.
Tony Blair, Labour's employment spokesman, said the attacks smacked of Tory panic. 'Only weeks after their election victory, they are in disarray over Europe, over the economy and even over their own organisation in Parliament. The reason for their panic is clear: John Smith will be the strong and effective Labour leader the country needs, leading a strengthened and determined Labour Party.'
The roughest Cabinet-level attack was delivered by Michael Portillo, Chief Secretary to the Treasury, who said Mr Smith, the shadow Chancellor, had been responsible for the economic package rejected by voters in April.
'John Smith's approach is inspired by the failed policies of the 1960s and 70s,' he told Cheltenham Conservatives. 'Labour will undoubtedly try and claim, over the next few years, that they have become reconciled to the market. But with John Smith at the helm, everyone will know that their heart is not in it.'
But the ministerial attack was muted by comparison with the Sun's headlines yesterday: 'He's fat, he's 53, he's had a heart attack and he's taking on a stress-loaded job. He may be leader but Smith can't get life insurance.'
The headline's assertion, unsupported by the quotes offered by insurance companies, echoed the Tory strategy of exploiting doubts over Mr Smith's health.
Ministers argue privately that if Mr Smith became Prime Minister, the country would be 'a heartbeat away' from having Mrs Beckett in Number 10. A Conservative Research Department dossier quotes her outright opposition to 1986 calls for the expulsion of Liverpool Militants from the party.
Union officials are today expected to acknowledge the need to pump more money into the Labour Party in return for a massive cut in costs. Larry Whitty, general secretary of the party, will make a presentation to representatives of more than 30 union affiliates in which he will promise to reorganise services and get rid of about one-third of the 200 staff at party headquarters.