The Department of Foreign Affairs has begun a Garda inquiry into the leaking of the confidential briefing document containing a conversation between an official and Prof Mary McAleese.
Amid expectations that a further document, potentially damaging to the Fianna Fail/Progressive Democrat candidate, will be published in two Sunday newspapers, the Government has had to set up the inquiry even though it does not believe it will produce results.
Before the first debate between the five presidential candidates on the Late Late Show, the Taoiseach accepted Mr John Bruton's assurances that he had not leaked the document last weekend.
"If he says he didn't do it, naturally enough I accept that," he said. These documents were highly restricted. Only a few people involved had access to them.
Asked why he had targeted the Fine Gael leader, Mr Ahern said it was extremely unlikely that someone could quickly refer to one particular document in a particular week out of 100 documents in that particular week. "Someone knew precisely what they were about, someone of a high political acumen," he said.
In Limerick last night, the Taoiseach said it was "doubtful whether there would be a satisfactory conclusion from a Garda investigation into the leaks from the Department of Foreign Affairs linking Mary McAleese with Sinn Fein".
Mr Ahern said "You could have a Garda investigation. But I could write the report myself at this stage. What would happen would be that the half-dozen or so people involved would say `Not me, sir. Somebody else'."
Fine Gael and Fianna Fail strategists, meanwhile, believe the latest controversy may consolidate party support for their respective candidates while breaking the high transfer pattern from supporters of all parties, and the two Independent candidates, to Prof McAleese.
There were indications in political circles last night that Mr Bruton's strong condemnation of Mr Gerry Adams's endorsement of Prof McAleese was designed to do this. Apparently aware of this, Mr Ahern urged Fianna Fail supporters to spend the campaign's penultimate weekend canvassing for their candidate.