The event on Wednesday will be the public climax of Mr Adams's two-week US tour, which began yesterday. The honour is usually reserved for US celebrities - the last recipients were the New York Rangers ice hockey team.
Alarm at the prospect of a propaganda triumph for Mr Adams prompted the British Government to fly Michael Mates, the former Northern Ireland minister, to the US yesterday by Concorde at the taxpayer's expense to spearhead a counter-offensive.
Mr Adams' tour began yesterday when he was greeted on landing at Boston airport by Senator Edward Kennedy, who compared his contribution to the Irish peace process to recent historical changes in the Middle East and South Africa. Mr Adams said: 'I appeal to John Major to use this oppportunity to make his mark in history as the one British prime minister who would work for peace in Northern Ireland.'
After Boston Mr Adams goes on to Detroit, Cleveland, New York, Philadelphia, Washington and Los Angeles. It is not clear who from the Clinton administration will meet him in Washington.
Both Senator Kennedy and Mr Guiliani will face accusations of exploiting the visit for electoral purposes.
Asked yesterday why such an honour was being conferred, Mr Guiliani's press secretary replied: 'If John Major can meet with Gerry Adams, then so can the Mayor of New York.' (Mr Major has never met Mr Adams.)
Mr Mates will be followed to America by John Alderdice, leader of Ulster's cross-community Alliance Party, whose trip is also being paid for out of public funds.
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