PLAID CYMRU last night dramatically offered to hold talks with Labour to stop any prospect of the Conservatives entering government in Wales.
The move was Plaid leader Ieuan Wyn Jones's response to the "lies" he claimed Labour was peddling in suggesting he was willing to serve in a Tory-led coalition.
Insisting he would not contemplate such a coalition he said, "Labour keeps peddling this story and therefore they are calling into question, frankly, my integrity.
"In a sense they are calling me a liar... It's time for Labour to stop peddling this lie, make it clear that they accept my word and not repeat it again."
The clash between Labour and Plaid dominated a day in which Chancellor Gordon Brown visited South Wales to help Rhodri Morgan's re-election campaign. Mr Brown warned the election could be "becoming a springboard for a Tory revival in Wales".
On a visit to the ultra-marginal Cardiff North constituency, Mr Brown said he was relaxed about Rhodri Morgan's "clear red water" policy approach, calling it a "healthy diversity".
Labour renewed its central allegation that Plaid was plotting to form a coalition with the Conservatives following an appearance by Mr Jones on Thursday evening's BBC Dragon's Eye programme. Pressed by presenter Rhun ap Iorwerth as to whether he would work in a coalition with Tory Ministers, Mr Jones said, "We would open discussions with all the parties, but there are two issues that I think are important for the people of Wales to know that we wouldn't do. We make this clear again so that the people of Wales are clear - we would not go into coalition under a Conservative First Minister and secondly we would not prop up a Labour Government either."
But Labour accused Mr Jones of "wriggling", saying that on seven occasions in the interview he failed to give a straight answer on whether Plaid would be prepared to work with Tory Ministers.
Welsh Secretary Peter Hain said, "Time after time, Plaid Cymru have refused point-blank to deny they would put the Tories back in power in Wales and allow Tory Ministers to take charge of Welsh public services. It is no longer tenable for them to refuse to answer the question.
"Only yesterday, (Plaid parliamentary leader) Elfyn Llwyd confirmed that Plaid Cymru would seek to agree a joint programme with the Tories. But Ieuan Wyn Jones still refuses to admit to the people of Wales what this would mean - Tory Ministers back in charge of Welsh schools and hospitals.
"Rhodri Morgan has stated categorically that there is no way Welsh Labour would ever work with the Tories in government in Wales.
"When the Tories were in power we suffered the two worst recessions in Wales since World War II. Unemployment was three times higher than it is today. This is the failed past which Plaid Cymru wants to land Wales with once more."
Later Plaid issued a statement from Mr Jones saying, "The Labour Party will not get a majority in this election. If no party has a majority, there's one simple way of keeping the Tories out - that is for Labour to talk to Plaid."
Rhodri Morgan did not respond directly, instead saying, "As Ieuan Wyn Jones made clear today, a vote for Plaid Cymru is a vote to allow Tory Ministers back into government in Wales. He failed to rule out the prospect of a Conservative Health Minister, or a Conservative Education Minister if they formed a coalition after May's election. A vote for Labour is a guarantee to stop that happening.
"There is a clear choice in front of the people of Wales. We are fighting on our record and on our manifesto to form a government. They are looking to cobble their manifestos together as part of a coalition."