The old adage “The harder I work, the luckier I get” simply does not seem to apply to Fianna Fáil leader Micheál Martin.

Even his political opponents, outside and inside his own party, are in awe of his unrelenting work rate and dedication to the job.

Yet the latest Irish Times/Ipsos MRBI opinion poll, published today, contains depressing reading for Mr Martin and his colleagues.

Politicians who do badly in opinion polls will always attempt to shrug off the results, in public at least. “There’s only one poll that matters,” is the catchcry.

A more immediate concern for the Fianna Fáil leadership is tomorrow’s Roscommon-South Leitrim byelection, which is taking place following Luke “Ming” Flanagan’s elevation to the European Parliament.

They are holding their breath in Fianna Fáil headquarters as pressure mounts on Mr Martin to deliver a seat for the party in the constituency. He has swapped Leinster House for Leitrim today and will knock on as many doors as possible before polls open.

The initial consensus in the constituency was that the byelection was Fianna Fáil’s to lose, and the party hit the ground running in the summer when it was first to select a candidate.

The low-key Ivan Connaughton, an auctioneer based in Athleague and Roscommon County Councillor, is well-regarded and remains the front-runner.

Hoping to give him a run for his money are Independent turfcutter Michael Fitzmaurice, the so-called "Ming" candidate; Sinn Féin's Martin Kenny, and Independent John McDermott (who was involved in an incident allegedly involving Fine Gael TD Frank Feighan last week in Co Roscommon).

Clearly much hinges on the outcome of this byelection for Mr Martin in a region which was once a Fianna Fáil stronghold.

Those glory days are obviously long gone for the party, but if Fianna Fáil fails to secure a seat in Roscommon-South Leitrim on Saturday, the development would represent more than a little local difficulty for the leader.

His track record on elections after the game-changing general election of 2011 has been good, however.

This May he managed to reinstate Fianna Fáil as the largest party in local government. On a day when Opposition rivals Sinn Féin did so well, this was quite an achievement.

The constant low-level grumbling about the direction in which Mr Martin is bringing the party was inevitably ramped up a notch or two today, prompting a blunt reaction from one Martin loyalist: “Some people court media attention by being negative, but they do f-all for the party.”

Asked on RTÉ’s Morning Ireland last month whether he was preparing to enter government after the next election, Mr Martin replied: “I am preparing to be Taoiseach.”

What else could he say if he wants to remain relevant? The game of politics must be played, but in truth the party must be looking at a two-election cycle before a trip back down the enchanted way to Government Buildings is even a prospect for Fianna Fáil.

The mantle of Uachtarán Fhianna Fáil is no longer glamorous or indeed personally rewarding.

The blunt reality is Mr Martin’s enemies within his own party would surely struggle to nominate someone who would be prepared to work as hard or be able to do a better job.