The former Liberal Democrat leader will reveal that Mr Blair did not abandon his plan to include senior Liberal Democrats in his cabinet when he won a huge majority in May 1997. Although the two leaders dropped the idea of an immediate coalition, they prepared to announce an historic two-party government twice since then.
Mr Ashdown's comments will alarm many Labour MPs and fuel speculation that Mr Blair remains committed to an eventual power-sharing deal with the Liberal Democrats."It's true to say that Tony Blair had planned and prepared for the possibility of a coalition for cabinet and it's true to say the size of the Labour majority disturbed those plans," Mr Ashdown will tell the Resigning Issues programme on BBC Radio 4 today. "It's not true, however, to say, as may not yet be generally known, that all thoughts of a coalition vanished at that point.
"This Rubicon of the two parties working together in government was a Rubicon I still wanted to cross and I believe he [Mr Blair] wanted to cross it. I believe it could be crossed in this Parliament and on at least two occasions there were moments when that could have been done for which we jointly prepared."
Mr Ashdown said a coalition could have been announced in the autumn of 1997 and a year later, when Lord Jenkins published plans to reform the voting system for Westminster, which ran into strong Labour opposition. "I don't blame that for not happening, I think the forces were so great that it would have been impossible to happen then," he said. Although he said a merger between Labour and the Liberal Democrats would be wrong, he insisted his views bore a "close resemblance" to Mr Blair's, and that a two-party partnership would help modernise Britain.
While regretting that he could not deliver it, he was sure it would happen sooner or later and hoped that Charles Kennedy, his successor, would revive the coalition plan after the next general election. Although Mr Kennedy has retained co-operation with Mr Blair on constitutional reform, he made clear yesterday his determination to distance his party from Labour before the next election.
Launching an alternative to tomorrow's Queen's Speech, Mr Kennedy said: "People throughout Britain are getting tired of this government's rather bossy tone. The Government should be promoting freedom rather than strengthening control. It needs to liberalise British society, decentralise British politics and deregulate the British economy." Mr Blair's aides played down Mr Ashdown's remarks, denying there were firm coalition plans. They suggested that the Prime Minister, in his talks with Mr Ashdown, may have been referring to a partnership in the long term.