From a situation where it was presumed in many quarters that nobody at all would challenge Michael D Higgins for the presidency, it now seems that a queuing system will be required for all those lining up to take a pop at him.

No fewer than three past and present panellists from the reality TV show Dragon’s Den are in the field.

Seán Gallagher announced this week that he would reprise his spectacular 2011 bid for the office, joining Gavin Duffy who has been campaigning earnestly but without much impact since July.

No sooner had Gallagher announced his intention, then he was joined by another “Dragon” (they seem to relish the description), Peter Casey, a businessman who has moved home from the US to offer his services to the country.

Senator Joan Freeman and the artist Kevin Sharkey have also been addressing county councils, seeking their support.

Sinn Féin will also run a candidate, and while the Ireland South MEP Liadh Ní Riada is widely touted as its nominee, the party has yet to officially decide.

The former Irish Independent journalist Gemma O’Doherty is also seeking a nomination, campaigning on an anti-corruption platform.

There are four weeks to go until nominations close. Hardly a day goes by without somebody new putting their hand up.

On Friday it was Mannix Flynn, the independent Dublin city councillor. He said he was considering standing himself because, in his view, the calibre of many of the candidates thus far was less than presidential. Flynn surely won’t be the last.

He has experience of running a national campaign. As a former Fianna Fáiler, he will be attractive – as he was in 2011 – to many Fianna Fáil voters who have no candidate of their own.

And he almost won seven years ago, when a spectacular late reversal overturned what looked on the final weekend like an unassailable lead. He still got over half a million votes.

Gallagher has done extensive research on a potential campaign, which includes where the weak spots of the incumbent might lie. But it will surely be a challenge to replicate the meteoric rise that characterised his last tilt at the presidency.

For a start, the country is different. Insurgent campaigns are difficult to repeat. Is Higgins beatable at all?

The history of elections tells us that very, very few candidates are unbeatable. Sure, many are very difficult to beat. But that’s a different thing.

Campaign polls On one reading of the numbers, Higgins is impregnable. Repeated Irish Times polls over recent years have shown strong support for a second term for Higgins, while a poll in the Daily Mail this week put his support at 66 per cent.

But campaign polls will be different, because the campaign dynamic will be different. And if there’s one thing we know about presidential elections in Ireland, it is that they are completely unpredictable. Unpredictable, and sometimes vicious.

Any reading of the history of the last election campaign in 2011 will attest the extent to which the media interrogated the candidates in succession, testing them to destruction – David Norris, Martin McGuinness, Dana Rosemary Scallon, Mary Davis and finally, Gallagher (Gay Mitchell never really got off the ground).

The name missing from that list is Higgins – who, by any fair reckoning, got away lightly last time. That is unlikely to be the case this time.

One thing Higgins will have to figure out is how he intends to separate the role of candidate from the role of President over the next two months. According to the Áras, he is “confident, based on legal advice available to him, that his campaign activity can be separated from his constitutional role”.

The Áras declined to share the legal advice. In reality, though, he could hardly avoid it and Higgins has already been using the office to campaign.

A good example recently was at the All-Ireland hurling semi-finals at the end of July when Higgins – unusually – was introduced to the players of the red carpet before the games, in full view of the crowds. This normally happens at finals (it will happen at the football final tomorrow) but it is usually not part of the semi-final routine.

Asked about it, the Áras said it was Croke Park’s idea. GAA sources, though reluctant to contradict the President, say otherwise. The President also gave a lengthy interview to RTÉ radio’s sports programme, mischievously (perhaps) recommending a bit of ground hurling.

Again, the Áras insisted this was RTÉ’s idea. Again, others differ. Either way, it’s probably not the last bit of ground hurling that Higgins’ opponents will see.

Higgins has all the advantages – of recognition, popularity, status and the strong approval of voters.

But before all that, he has the single greatest quality that any politician can have: people like him. They warm to his beaming smile, and his obvious delight in doing the job.

But those who have worked with him over the years also say that he has an irascible, impatient side, and is capable of flashes of anger and frustration directed at those close to him.

As President, he has been afforded an exaggerated level of respect and deference, as befits the office. He would hardly be human were he not affected by that, so it may be something of a challenge to maintain his sangfroid when reporters are shouting questions at him about the hotel bills for foreign trips, or the presidential wardrobe, or his admiration for Latin American strongmen, or whatever.