Martin needs TDs to back his right to a sincere position on the Eighth
Local political wars were often Fianna Fáil's greatest stock in trade and made elections fizz. But for all the party's history, its loyal members have avoided national rows and tried to make loyalty to the leader an immutable core value.
Epic battles between constituency rivals, centred on gutsy rows about packed conventions and would-be dastardly efforts to keep one or other potential runner off the ticket, were often less than edifying.
But these "auld rows" also got people talking about politics and often got lethargic voters out to polling stations. They were another part of the reason why Fianna Fáil succeeded so hugely since Éamon de Valera led his supporters into Leinster House back in 1926.
The only exception to all that came in 1970 in the wake of the Haughey/Blaney/Boland arms for Northern Ireland controversy. For a time, the Fianna Fáil leader of the day, Jack Lynch, was seriously challenged and he had to call on all the party's tradition of loyalty to successfully hang on.
Like all Irish political certainties, this Fianna Fáil core value cannot be taken entirely for granted these days. It was eroded back in June 1989 when the "natural party of government" first decided to share cabinet seats with its former hated rivals in the Progressive Democrats. The party's later embrace of the so-called "FF gene pool" - where the party mavericks, elected as independents, were also taken into the government tent - was a further dilution of that immutable discipline.
The persistence of party loyalty to the leader now faces another test, one involving the most divisive issue of abortion, which has befuddled the Irish nation for almost 40 years. Fianna Fáil leader Micheál Martin has deeply upset a large number of his parliamentary party colleagues by his declaration last Thursday in Dáil Éireann that he favours significant change to the country's abortion regime. His statement is against the trend of the majority of his TDs and senators on the issue, and it is notable that 70pc of the membership voted against change to the current situation at the party ard fheis last October.
On Friday and Saturday, we heard dissenting voices from the Fianna Fáil parliamentary party, many of whom were taken unawares by the timing and unexpected nature of their leader's intervention. Some of these, notably Carlow-Kilkenny TD Bobby Aylward, spoke of the need for those who are "avowedly pro-life" to come together and articulate that view.
The ever-courteous Brendan Smith of Cavan-Monaghan diplomatically stressed the word "disappointment" - which he was strongly picking up among local members and supporters. The word disappointment has serious connotations, and other deputies privately spoke of considerable anger at their leader's move.
Now we find a Fianna Fáil party activist from north Kilkenny, Seán D Rafter, launching an online petition that denounces Micheál Martin's stance on the issue and calls for his replacement. "Micheál Martin does not represent us. It's time for somebody new, somebody with the courage to represent the millions of ordinary pro-life people in our country," the online petition concludes.
Mr Rafter, a young barrister on the South Eastern Circuit and former Leinster House intern for the party, argues that Fianna Fáil's work has to be more about core economic issues of development and jobs. He also argues that the party "is the most pro-life" of all the political groupings in the country and its stance in the upcoming referendum should be framed accordingly: it must back retention of the 1983 Eighth Amendment.
Well, this is all very politically awkward - but it is not necessarily politically fatal. The reality is that Mr Martin's stance has a ring of truth and sincerity about it. It may also be more in tune with the public mood than the bulk of his parliamentary party or his party membership, petition or no petition.
Some TDs who strongly oppose repeal of the Eighth, notably veteran Willie O'Dea of Limerick City and newcomer Pat Casey of Wicklow, have said they respect their leader's right to avail of the free vote given to everybody in the party. Mr O'Dea has also applauded the leader's courage and said it contrasts with the "shilling-each-way" approach of the Taoiseach Leo Varadkar.
In a very telling comment, Galway East TD Anne Rabbitte, who has a more nuanced position on the issue, urged colleagues "to take a step back".
Ms Rabbitte seemed to be saying: Many TDs utterly oppose repeal. But do they really want to bet their party's fortunes on this divisive issue?
We will learn over the coming days how serious the matter is for the Fianna Fáil leadership. But it is clear Mr Martin needs all his TDs and senators to support him now, if he is to avoid damaging conflict.