Joe Biden left Ireland in the early hours of Saturday vowing to run again for president, promising to formally announce his decision to run for a second presidential term “relatively soon”.

At the same time he spoke of his hope of an epoch of renewal in Northern Ireland, restating the “incredible” US investment opportunities that lay ahead if peace endures.

Speaking to reporters in Ireland before leaving Ireland West airport on the last leg of his four-day visit to Ireland, Biden was asked whether the last few days had changed his calculus on when to make his announcement on his plans to run.

“No, no I have already made that calculation. We will announce it relatively soon,” he said.

“The trip here just reinforced my sense of optimism about what can be done. I told you my plan is to run again.”

Arguably, the speech was pitched at the US teatime audience to put to bed voter doubts that, at the age of 80, he is too old to run for another term in the White House.