Ireland’s prime minister has suffered a last-minute collapse in support as rivals Sinn Fein gained ground in the final days of the country’s snap election campaign.

The latest poll showed Simon Harris’s party dropping six points following an awkward interaction with a care worker on the campaign trail.

Mr Harris at 37, is the youngest ever Irish prime minister and has overseen a dramatic upswing in Fine Gael’s fortunes after succeeding the unpopular Leo Varadkar, who resigned as leader in April.

He overturned a commanding Sinn Fein lead in the polls in June that had lasted for two years and defeated his rivals in local and European elections.

The “TikTok taoiseach” – so-called for his canny use of social media – called a general election four months early after outflanking Sinn Fein on immigration and launching a giveaway budget.

But on Monday, just four days before Ireland votes, the “Harris hop” was being dubbed the “Simon slump”.

The Irish Times/Ipsos poll, the last before the election, had Fine Gael dropping six points from first position in the polls to third and 19 per cent of the vote.

Sinn Fein are up one point at 20 per cent in the Monday poll.

Fianna Fail, led by former taoiseach Micheal Martin, are up two points to become Ireland’s most popular party on 21 per cent.

It has overtaken Fine Gael, its coalition partner in government, for the first time since Mr Harris became leader.