But Oliver Letwin has strongly denied being the source for the £20bn tax cuts figure - which contradicted the Tory manifesto's commitment to cut only £8bn in the first two years of the next parliament.
" I spoke to the FT but I never said to them the Conservative Party was committed to £20bn of tax cuts "
Mr Letwin, MP for Dorset West and deputy to shadow chancellor Michael Portillo, had gone to ground after suggestions that he was responsible for the disputed tax figure, which appeared in the Financial Times.
Chancellor Gordon Brown taunted the Tories over Mr Letwin's low profile at Labour's Tuesday news conference, saying: "Let Letwin speak. We should free the Dorset One!"
Out of hiding
But on Wednesday morning the accused came out of hiding to campaign in Stroud - and to issue a denial.
Mr Letwin said: "I spoke to the FT but I never said to them the Conservative Party was committed to £20bn of tax cuts.
"If you look carefully at the story in the FT you will see that they did not say that is what I said.
"What I told them was what our tax policy is.
"It starts with £8bn of costed tax cuts which benefit savers and pensioners and motorists and which we have laid out in some detail."
He added: "Michael Portillo and William Hague have both made abundantly clear that is not the limit of our tax-cutting aspirations."
Earlier in the week it looked like the apparent disagreement over tax might blow the Tories' election plans off course, as Mr Hague was dogged with questions about the disputed figure.
Labour produced a 'wanted' poster featuring the elusive MP, mocking his conspicuous absence.
But Mr Letwin, who has described himself as "a radical Thatcherite", said he was amused that the focus was on him and not "the great difference between the Labour Party's plans, which include raising taxes, and ours which include cutting taxes".
Labour's campaign co-ordinator Douglas Alexander has now challenged the Tories to put Mr Letwin on the platform at their next news conference.
He said: "If he had stood by the figure of £8bn of cuts in his briefing to the Financial Times they would not have had a story and he would not have had to go into hiding."
"The truth is that he let the cat out of the bag and started talking about the Tories agenda of £20bn of cuts in public spending which would devastate essential public services."