With more than five weeks to go, the first mud of the presidential election campaign has landed noisily on Adi Roche. The early opinion poll leader's rather wholesome and saintly image has been questioned by a sustained barrage of accusation that she is in reality a bullying and unpleasant person unfit to be President.

With the other candidates still adopting a relatively low profile, the questioning of Ms Roche's style and personality has received major coverage and attention. The long-term effect of the flurry of criticism is difficult to gauge, but its surprise emergence illustrates the unpredictability of the contest and the likelihood that unplanned events during the campaign may prove decisive, as the late Brian Lenihan discovered last time.

It is difficult to see how a campaign to damage Adi Roche could have been better organised. Claims that she is an iron-fisted Stalinist who verbally abused and insulted her staff as manipulative, lazy, incompetent and useless dominated the first weekend of the campaign and are set to run at least until the end of this week.

The eruption of the story out of nowhere on to the front pages of four national Sunday newspapers gave it maximum impact. It was put at the top of broadcast news bulletins throughout Sunday and led yesterday morning's newspapers. A group of Ms Roche's alleged victims held a much-publicised and photographed meeting in Cork on Sunday night. Yesterday one of them was interviewed at length on RTE radio's Today With Pat Kenny, another spoke on the News at One, another on Liveline. And they are promising more to come.

Additional information will be released tomorrow, they have said, ensuring that the media will stay interested at least until then.

The Roche campaigners' defence strategy is two-pronged. Firstly, they reject most of what has been said as an unfair caricature. Secondly, they say that in so far as some of it may be true, it is actually a reason to vote for her.

The first part of the strategy was enacted yesterday and on Sunday by Ms Roche and some of her supporters. Ms Roche herself rejected the claims that her alleged "bullying and dictatorial" manner had forced staff and volunteers with the Chernobyl Children's Project to resign. A group of representatives of the project came out in her support, rejecting the portrayal of Ms Roche by the disaffected group.

Throughout yesterday supporters of Ms Roche, including Ruairi Quinn, Fergus Finlay, John Gormley and Patricia McKenna turned up on radio and television to support her.

Mr Quinn, the chairman of Ms Roche's campaign committee, employed the second element of the strategy last night on RTE news. The suggestion that Ms Roche was a tough person who got things done was in fact a good thing, he said. Up to now she had been portrayed as "a saintly figure who wouldn't be able to cut it in the real world".

Despite the blanket coverage, it is difficult to discern a substantial allegation. Claims that Ms Roche has a tough, dictatorial or Stalinist management style certainly provide a contrast to her public image, but they do not amount to allegations of anything improper.

The allegation that Irish families who took in Chernobyl children were not vetted properly have been hotly disputed by the Chernobyl Children's Project, which says procedures satisfactory to the health boards are in place. The opinion of some of those formerly associated with the project that Chernobyl children should not be brought to Ireland at all is a questioning of the fundamental basis of the project rather than a personal criticism of Adi Roche.

Labour Party sources yesterday put forward a conspiracy theory to be considered by the media. "Prima facie it's unusual - and does not appear accidental or coincidental - that this story appeared in four papers on the same day", the sources said. "If people had been harbouring these feelings, why did they wait until now to disclose them to the public unless they had a particular purpose in mind?"

The particular purpose suggested by the Labour sources is to damage Ms Roche's campaign to become President.

"But at this point they have just cried wolf," the sources went on. "At some stage the media's patience will wear thin and you will start to ask them to produce evidence that what they are saying is anything more than abuse, opinion and hearsay."

Her critics have plenty of time in which to stand up their suggestion that Ms Roche's management style and personality make her unsuitable to become President of Ireland. And if there is a conspiracy, the Roche campaign has plenty of time to prove it.

It is therefore too early to say whether the emergence of a group of critics will cause lasting damage to the Roche campaign. There is plenty of time for the public and the media to assess how serious the allegations are, and whether they relate to serious wrongdoing or merely a no-nonsense temperament. Further statements by the disaffected are awaited with interest.

If the image sticks, it could lose her some of the fickle, floating votes her campaign hopes to attract. The Labour Party chose her for her young, idealistic and committed image, which it believes will attract young voters who are suspicious of the political establishment. If she emerges as a tough authority figure who chews up those who get in her way, her attractiveness for the anti-politician voters could be dimmed. as trainees.

With more than five weeks to go to polling day, any negative effect on Ms Roche's campaign has time to wear off. What lasting damage was done to Mary Robinson by her period as an iron-fisted Stalinist, shortly after her election, when she fired a number of staff at Aras an Uachtarain?

If the accusations merely add a veneer of toughness to a person already acknowledged as compassionate and caring, she may even gain from the present exchanges.

She is already leading in the opinion polls, and after this week she will have conquered any problem of voter recognition. The ability of her accusers to produce hard evidence, and of her campaign to counter it, will determine whether on polling day Adi Roche is seen as young, idealistic and a bully, or simply young, idealistic and tough.