Micheál Martin’s leadership has been under pressure before, but the Fianna Fáil leader has rarely been so vulnerable as he is now. And the monumental screw-up of the Jim Gavin presidential candidacy has left TDs and grassroots alike seething. [ Maybe some of us are just not meant to be presidentOpens in new window ]That is not, however, to say that Martin’s leadership is in its last days. The man most talked about as the successor to Martin is the Minister for Justice, Jim O’Callaghan. Speaking to RTÉ at lunchtime on Monday, Wexford-Wicklow TD Malcolm Byrne was critical of the party leadership but shied away from joining any putative rebellion.