Labour yesterday accused the Tories of a "disgraceful" smear campaign after it was disclosed that right-leaning commentators in the US had been sent a list of the Labour leader's alleged "un-American activities" since he entered politics in the early 1980s.
The move appeared to underline Tory anxieties that in contrast to Neil Kinnock's ill-starred trip to Washington before the 1987 election, Mr Blair's carefully planned visit to New York and Washington this week, culminating in talks with President Clinton at the White House, is likely to receive favourable media attention both here and in the US.
Labour condemned the move as a "pathetic stunt" which breached the protocol that British politicians do not attack each other abroad.
Conservative Central Office said it had merely borrowed a well-worn Labour tactic to provide sourced quotes for people "who are curious about how he has voted and why".
The paper - headed in an echo of the notorious McCarthy congressional committee in the 1950s "The Labour Party's Un-American activities" - rehearses fairly routine, if heavily partisan and selective, charges against Mr Blair.
These include accusations that he had, for part of the 1980s, been a member of CND, had criticised the US bombing of Tripoli in 1986, and had attacked the US's "evil campaign" against Nicaragua and elsewhere in Central America as late as 1988.
The paper appears to have made little impression on US commentators, with one Wall Street Journal editor reportedly describing it as "juvenile".
The document relies partly on guilt by association and points to the existence of the "secretive" left-of-centre supper club - which, it says, includes five members of the Shadow Cabinet and which was opposed to the Gulf war.
In fact, Mr Blair - like Neil Kinnock, the then Labour leader - was strongly in support of the Allied liberation of Kuwait, though the document does not make that point.
It argues that both Mr Blair and his wife Cherie were "anti-nuclear and anti-American" in 1983 when they joined the Labour co-ordinating committee which subsequently became a "soft-left" vehicle for combating Bennism in the party.
Labour claimed yesterday that if John Major had authorised the document then it indicated he was prepared to put party politics above his own relationship with President Clinton.
But Brian Mawhinney, the Tory party chairman, said: "If Mr Blair is so ashamed of the things he has said, will he now withdraw them?"
New Labour research suggests that the party's membership is now more middle class than that of the Conservatives. Figures show that of members paying the full fee of pounds 15 per year, around half the total membership - which is projected to go over 400,000 by the end of the year - 57 per cent are in households earning pounds 20,000 or more and 30 per cent are in households earning pounds 30,000 or more.
Comparable estimates of Conservative Party membership is that 45 per cent earn pounds 20,000 or more. One reason may be that Labour has a much younger membership, with an average age of 43 compared with an estimated 62 years of age for the Tories.