Wicklow/East Carlow TD Stephen Donnelly pictured last year with his Social Democrat co-leaders Roisin Shorthall and Catherine Murphy. Photo Tom Burke

The split within the Social Democrats that led to the departure of Stephen Donnelly dates back to the refusal by the party to enter Government formation talks.

The Irish Independent understands that the Wicklow/East Carlow TD was keen to engage with Fine Gael and Fianna Fáil about the prospect of being in coalition.

However, Mr Donnelly's co-leaders - Róisín Shortall and Catherine Murphy - opposed the move.

Relations between the TDs have been strained in recent months, culminating in Mr Donnelly's decision to quit the party yesterday.

Sources say the "final straw" was a disagreement over the party's response to the European Commission's ruling that Apple was given a sweetheart deal worth €13m by Revenue.

Ms Shortall and Ms Murphy became "frustrated" after apparently being unable to make contact with Mr Donnelly over a proposed press release outlining the party's stance on the controversial issue.

Read more: Stephen Donnelly quits Social Democrats - but has yet to decide to whether to go solo or join a party

Hours later, while Mr Donnelly went on radio to offer a measured analysis, his party colleagues were staunch in their view that Ireland should collect the back taxes.

A number of party sources last night said Mr Donnelly's decision to resign had been anticipated for some time.

The same sources said Mr Donnelly told Ms Shortall and Ms Murphy that he intended to use the month of August to consider his future.

In a statement yesterday, the party took a swipe at Mr Donnelly, saying he chose to "walk away" from the Social Democrats.

"The levels of dedication required for such a major undertaking can be overwhelming for some," the statement said.

"However, our elected councillors, our staff team and our volunteers are passionate about our project and we will now get on with the job of building our party."

Both Ms Shortall and Ms Murphy spoke on radio yesterday, expressing their disappointment at the decision.

Ms Shortall said Mr Donnelly had become "somewhat disengaged" from the party in recent months.

Mr Donnelly did not respond to calls by the Irish Independent.

However, he told Mary Wilson on RTÉ's 'Drivetime' programme that being a member of the Social Democrats "just isn't working for me".

He rejected suggestions that he is not a "team player" and said he feels he cannot serve the country to the best of his ability within the Social Democrats' fold.

Mr Donnelly also agreed that all politicians should aspire to be in government.

"If you're asking me straight, would I love to be in government one day, of course I would," he said.

Meanwhile, there is now speculation that Mr Donnelly may decide to join another party.

Asked whether he would consider an approach from a party such as Fianna Fáil, Mr Donnelly said that the issue was not at the forefront of his mind.

"That's exactly the kind of conversation I'm going to have with my supporters in Wicklow over the next few days and the next few weeks," Mr Donnelly added.

Fianna Fáil sources last night said that they are open to the idea of approaching Mr Donnelly.

Mr Donnelly's decision to quit also threatens the party's speaking rights in the Dáil.

At present, the Social Democrats are in an arrangement with the Green Party which allows them to avail of a slot during 'Leaders' Questions'.

However, that arrangement may be rescinded unless Mr Donnelly agrees for it to remain intact.

Meanwhile, the Social Democrats' sole councillor in Mr Donnelly's constituency yesterday confirmed that she will remain in the party despite the decision.

Jennifer Whitmore, who was seen as being extremely close to Mr Donnelly, is now being lined up to oppose him ahead of the next general election.

Irish Independent