The two leaders secretly discussed detailed plans for "a partnership of principle" in the year before the general election, according to the new biography of Peter Mandelson, who acted as Mr Blair's go-between with the Liberal Democrats.
The disclosure will fuel speculation that Mr Blair will seek a Lib-Lab coalition if his majority is reduced at the next election. It will anger cabinet ministers opposed to close links, including John Prescott, Gordon Brown and Jack Straw, who were kept out of the discussions in the run- up to the 1997 election.
Under the secret Blair-Ashdown agreement, two or more Liberal Democrats would have joined the Cabinet, while other Liberal Democrats became junior ministers. Mr Ashdown has always insisted that he was not personally intending to join the Cabinet.
The plan was to be implemented in the event of a hung parliament and if Labour won an overall majority of up to 50 seats. Mr Blair was still expecting a majority of that order when he spoke to Mr Ashdown on polling day. However, Mr Blair went much further during a telephone conversation with the Liberal Democrat leader on polling day, according to Donald Macintyre's book, Mandelson: The Biography. Mr Blair believed that "a larger than expected majority would increase rather than reduce the possibility of 'doing things' with the Liberal Democrats. In other words, it might actually be easier to bring them into a coalition." Mr Ashdown agreed. But by the next morning Mr Blair had a majority of 179 and his mood appeared to have changed.
Mr Ashdown, too, was hesitant. He refused to walk into Downing Street until a deal had been done, which made negotiations on the morning after election day more difficult.
The Liberal Democrat leader shared Mr Blair's doubts, on the grounds that the people had voted overwhelmingly for a Labour government. Although the plan was shelved, Mr Blair stressed that he wanted closer co-operation with the Liberal Democrats, and instead invited them to sit on a cabinet committee on constitutional reform.
The truth was 'out', Review Front