'As regards to Minister O'Dea I don't have confidence in him. His situation is compromised. Probably be a few chapters in this story yet".

TWENTY-four words, tweeted at 6.30pm on Wednesday by Green Party chairman Dan Boyle, sealed Willie O'Dea's fate. Twenty-four hours later, O'Dea was drafting his letter of resignation to his friend, Taoiseach Brian Cowen.

The former defence minister has nobody to blame but himself for his demise, but there is no question that Boyle's intervention, via Twitter, was the catalyst for his resignation. Before that, the widespread view in Leinster House was that O'Dea would survive. His government colleagues, including the Green TDs, had just voted confidence in him, which seemed to draw a line in the sand on the issue. O'Dea was damaged, certainly. He could forget about promotion in any upcoming reshuffle, but the ministerial car would still be parked outside his clinic on Saturday morning.

Boyle regularly gets on the nerves of Fianna Fáil figures and his solo runs haven't always endeared him to his Green party colleagues either. But this time, his comments accurately reflected the deep unease within the parliamentary party at what they had just done.

The ink of the party whips' signatures on the vote of confidence was barely dry before senior Green Party figures started to have second thoughts about what had just happened. They had found themselves in the middle of a confidence motion before they knew what hit them – evidenced by the normally articulate Eamon Ryan's painfully poor and wholly ill-prepared speech "backing" O'Dea – and they certainly weren't going to side with the opposition on the motion.

But they weren't impressed at being "bounced" into an early hearing of the motion (there wasn't even time to hold a meeting of their parliamentary party) and it was clearly with heavy hearts that they trooped through the voting lobbies. It wasn't going to take much to change their stance.

Immediately after the confidence motion, the Greens finally got to have their parliamentary meeting, which began at 5.30pm. Boyle wasn't in attendance as he was required in the Seanad. "We were still in the meeting when [word came through] Dan had tweeted," said one insider. Suddenly everything had changed.

Not long afterwards, the Green leadership began to get word of what the following morning's Limerick Leader would contain. Earlier, just before 3pm, Willie O'Dea had popped into John Gormley's office down the hall of the ministerial corridor in Government Buildings to reassure him that his position would be vindicated by what was in the paper.

But Gormley was not happy with what he was reading. The short time between O'Dea's now infamous interview with Limerick journalist Mike Dwane and the inaccurate affidavit he swore in relation to the matter was particularly striking for the Greens. How could O'Dea have forgotten, in such a short period, the very strident comments he had made to Dwane?

Fair and accommodating

Gormley and other senior figures liked O'Dea, something that had surprised them on coming into office. They found him fair and accommodating. But the feeling that the party was defending the indefensible was getting stronger and stronger. Paul Gogarty, Green TD for Dublin Mid-West, went on Morning Ireland on Thursday and, in difficult circumstances given that Boyle's comments had by now been widely reported, did a decent holding job, keeping the Greens' options open.

But phone calls were taking place within the party. The coverage in that morning's newspapers made for painful reading. Party member and former councillor Vincent P Martin had written a devastating critique of O'Dea's actions in the Irish Times.

The opposition, sensing blood, piled the pressure on the Greens by kicking up on the order of business in the Dáil and putting down another motion of no confidence in O'Dea, this time in the Seanad. The motion had no chance of success, but it put Dan Boyle in an invidious position. Would the senator vote with the government, despite his public declaration that he had no confidence in O'Dea? Or would he side with the opposition parties who were patently trying to drive a wedge between Fianna Fáil and the Greens?

By midday, the parliamentary party was meeting in its room at Agriculture House. After a break for Dáil votes for around an hour, the meeting resumed. At 2pm, copies of the Limerick Leader article were distributed and read.

Two of those present had heard Seán O'Rourke's News at One interview with O'Dea. The same programme had also played the audio from O'Dea's interview with Mike Dwane for the first time. The transcript of the interview had been widely published but actually hearing had a devastating impact.

"Questions were being asked about the tone of what he said on the tape and the way he was portraying himself as a victim [in the interview with O'Rourke]," one insider said.

The mood was calm in the Green meeting but there was serious concern over several issues: the tone of O'Dea's language in the recording, his belligerent delivery in the Dáil the day before, the questions about garda sources and the Limerick Leader not vindicating him.

"Some people felt O'Dea had done enough to warrant going the day before. Others felt there was a case for it to be dealt with fairly and there was no need for a witch-hunt. We weren't prematurely clamouring for his head but we gave him due process. We were willing to look at the facts so we looked at it rationally. But we knew that his position was politically untenable," a source said.

The Sunday Tribune has also learned that the meeting tried to "look at ways and means" where O'Dea "could still have an honourable way" of stepping down. "We spent a while looking at [the option of] him resigning temporarily, like Peter Robinson did in the north, and getting the Standards in Public Office (SIPO) commission to look into it," the source confirmed.

But it was felt that SIPO wouldn't have the necessary powers to investigate, so those present agreed it was up to them to make a judgement purely on the evidence before them.

It quickly became obvious that all of those present felt O'Dea could not continue. The view was that O'Dea hadn't done anything to win sympathy. There would have been continuing pressure for him to reveal his garda source and there would have been no way to stop the stream of questioning.

It wasn't long before their colleagues on the Fianna Fáil benches were coming to the same conclusion. Despite sounding contrite on the News at One, O'Dea had managed to dig himself into an even bigger hole. While there was none of the ill-advised bravado of his previous day's Dáil speech, he unwisely suggested that he too was a victim.

More damaging perhaps was his answer to a question from O'Rourke as to whether he would cooperate with any inquiry into how he had received what proved to be inaccurate information from the gardaí pertaining to Sinn Féin councillor Maurice Quinlivan.

"I was told the thing off the record in casual conversation and I'll cross that bridge when I get to it," O'Dea responded. Pressed further by O'Rourke, he added: "Of course I'd cooperate. How far I'd cooperate I don't know. I'll certainly cooperate to the best of my ability."

Dead man walking

That must have sent alarm bells ringing in the head of the listening Taoiseach. It's true that the whole question of a garda inquiry was something of a red herring – it was never going to come to anything – but it didn't sound good to hear a minister hedging his bets on the matter.

O'Dea was now politically a dead man walking. It didn't help that he was one of several Fianna Fáil TDs who did not turn up for a series of votes in the Dáil, which led to the government coming dangerously close to being defeated. There was some muttering among Fianna Fáil TDs that, as they had all queued up to vote confidence in him the previous day, the defence minister should have been in their midst to vote for the government.

Not long after the News at One interview, the Taoiseach did a door-step interview with reporters. Although he went through the motions of pledging support for O'Dea, Cowen didn't elaborate on his answers and it was a less than wholehearted endorsement of his minister. His body language suggested that he knew what lay ahead.

Shortly afterwards, at around 2.30pm, the Taoiseach got a phone call from O'Dea in which, it is being claimed by Fianna Fáil, the minister signalled his intention to resign.

At around 3.30pm, Gormley met the taoiseach; the Greens' line is that he clearly signalled that O'Dea's position was untenable. It was a spiky encounter. Cowen, a stickler for protocol, would probably not have told Gormley about his conversation with O'Dea, as he would have regarded that exchange as private. But it is understood that Cowen did ask Gormley not to go public at this point.

"Cowen didn't want us calling for his head so we didn't," said one Green source this weekend.

By this stage Dáil Eireann was buzzing with rumours that O'Dea was on the way out. There are conflicting accounts as to when the resignation was agreed. Did it happen in that 2.30pm conversation between Cowen and O'Dea or was it sometime after Gormley's meeting with the taoiseach? Fianna Fáil is anxious not to have it appear that it was doing the bidding of the smaller party. But Willie O'Dea's comments on Friday make it clear he felt the Greens forced the issue.

Humorous aside for the Greens

Whatever the chain of events, there is no question that the Greens were instrumental in O'Dea's going. As early as lunchtime, it was obvious to Brian Cowen that the Greens couldn't live with O'Dea in the cabinet. The News at One interview drove the nails into his political coffin.

O'Dea and the Taoiseach are believed to have had another telephone conversation at around 6pm, by which time the matter would have been clear-cut. All that was left was the formalities.

Amid all the tension, there was a humorous aside for the Greens. The Six One News reported that the Green parliamentary party had returned to its deliberations at 6pm but in fact the only reason the TDs and senators had got together was to tune into that very news bulletin.

But there was nothing funny about what was to unfold as O'Dea's resignation was formally announced just before 9pm on Thursday evening. There was obvious tension between the two parties over a statement issued by the Greens and a subsequent interview given by Gormley to RTE's Nine O'Clock News.

The Greens felt they had to provide justification for their extraordinary u-turn in first voting confidence in O'Dea and then, the following day, saying his position was untenable. The party statement expressed concern at O'Dea's comment that his original actions were "based on information given to him by An Garda Síochána" and described as "inappropriate" O'Dea's "comments and conduct during yesterday's debate and in subsequent media appearances".

"All these factors have led us to conclude that Willie O'Dea could not continue as a member of this government," the statement said.

Gormley echoed these sentiments minutes later on television, much to the annoyance of Fianna Fáil figures who felt this was inappropriate as the minister had just lost his job.

By then O'Dea was on his way back to Limerick, no doubt wondering how and where it had all gone wrong. Last weekend, the issue had barely registered on the political radar but, after three tumultuous days in Dáil Eireann, it had brought down one of Fianna Fáil's most senior figures. A tweet, it seems, is a long time in politics.