The former minister for foreign affairs, Mr Ray Burke, is set to reject all allegations of planning corruption when he makes his long-awaited appearance at the Flood tribunal today.
Mr Burke is expected to deliver a strong attack on Mr James Gogarty, the retired building company executive who has accused him of taking an £80,000 bribe in return for planning favours.
But his evidence could prove highly embarrassing for the Taoiseach, Mr Ahern, who interviewed Mr Burke regarding the allegations before appointing him to the Cabinet in June 1997.
Mr Ahern, who has never divulged the content of these discussions, said at the time he was satisfied that Mr Burke could be appointed. Since then, however, he has given varying accounts of what he knew about the allegations at the time. Mr Burke resigned in October 1997 in a controversy over the issuing of passports to a wealthy Arab family.
The possible political fallout for Fianna Fail is diminished somewhat by the fact that the Dail rose last Friday for the summer recess. Mr Burke was originally scheduled to give evidence last week but his appearance was delayed.
According to political sources, Mr Burke remains angry at the treatment he has received from Fianna Fail and in particular the Taoiseach.
Mr Burke accepts he was paid £30,000 at a meeting in his house in June 1989, at which Mr Gogarty and the developer Mr Michael Bailey were present. But he insists he understood the money to be an unsolicited political donation.
He originally told the Dail that the money was paid entirely in cash, but today he is expected to say that the £30,000 sum included a cheque for £10,000. He furnished a brief statement denying the allegations against him earlier this year. Contrary to reports, he has not filed a second statement.