One of the longest-serving members of Dáil Eireann, Ms Harney explained she felt someone who was not running in the general election should not continue to serve in the Cabinet.
Shortly afterwards it was announced that the Taoiseach had also received letters of resignation from three other ministers; Noel Dempsey, Dermot Ahern, and Tony Killeen.
Including Micheál Martin, who tendered his resignation on Tuesday night having lost the motion of confidence vote in Brian Cowen as party leader, five ministers have left the government in 24 hours.
In terms of a future leadership contest, Mr Martin's is well-placed should a vacancy arise. He has also almost guaranteed himself re-election in Cork South-Central – the Rebel county loves a rebel and it now has one in the former Minister. Despite losing the confidence vote, Micheál Martin has emerged as a strong contender for the Fianna Fáil leadership as the other pretenders – Brian Lenihan and Mary Hanafin – misjudged the situation entirely.
By openly supporting Cowen and claiming he had to shelve all personal ambition due to the weight of the Finance portfolio, Brian Lenihan has drawn the rancour of some backbench TDs. Seán Power and John McGuinness maintain the Finance Minister expressed an interest in leading the party, apparently going so far as to encourage backbenchers to "look at the numbers" for a motion of no confidence in Brian Cowen.
Meanwhile, in her refusal to state her position on the issue, Mary Hanafin effectively made herself irrelevant in the leadership contest. On Tuesday evening, she told the parliamentary party she would vote in accordance with the views she expressed privately to the Taoiseach. Yesterday she finally revealed that she voted against the Taoiseach, but her admission has come too late in the game to be of any real significance. Positive significance that is, for it has certainly damaged her credibility as she plans to stay on in Cabinet despite having voted no confidence in Brian Cowen.
It is believed the four resignations last night, which left vacancies in the ministries of Health, Transport, Justice & Law Reform, and Defence, were planned in order to allow for a Cabinet reshuffle.
In what some have called a deeply cynical move, Mr Cowen will now bring some new faces to Cabinet with weeks to go before the general election. According to the Green Party, the election will be held in March. Thus the reshuffle looks to be part of a seat-saving strategy.
This is the first sign of Fianna Fáil attempting to enter election mode; descriptions of a 're-energised' party and a 'rejuvenated' Brian Cowen will emerge from Fianna Fail in the coming weeks. Indeed, yesterday evening An Taoiseach dispatched an email to party supporters criticising what he described as 'Labour Negativity' and attached a video of his performance in the Dáil yesterday afternoon in which he attacked Labour leader Eamon Gilmore for practising the 'politics of negativity'.
In early December, Noel Dempsey circulated a similar email in relation to an interview the Taoiseach gave to RTE's Prime Time, supporters were encouraged to share the video with friends via social media.
Whether the public will be won over by this apparently 'revitalised' Fianna Fáil party is questionable. People reacted negatively across social media to the so-called Fianna Fáil heave which dominated the airwaves over the past week. It was perceived by many as a clear example of Fianna Fáil putting its own interests before those of the country.
This latest move will no doubt be viewed with great cynicism by members of the public; the mood is ripe for an election – it has been for some time – and the reshuffle may be seen as a further attempt by Brian Cowen to delay this process, clinging obstinately to power.
Watching Fianna Fáil over the past week has been a surreal experience; the bizarre civility of a much hyped but ultimately underwhelming leadership contest between Micheál Martin and Brian Cowen; Brian Lenihan falling out of favour with backbench TDs; and now four resignations and a Cabinet reshuffle with only weeks to go to a general election.
As Vincent Browne so aptly put it earlier in the week, "It would do your head in, wouldn't it?"