(Reuters) - Former Irish Republican Army (IRA) commander Martin McGuinness has slipped to fifth from third in the race to become Ireland's president, a poll showed on Sunday, as his Sinn Fein party struggles to match its success in Northern Ireland.

After a wave of criticism of his violent past and accusations he is misrepresenting the extent of his role in the IRA, support for McGuinness has fallen over the last two weeks to 11 percent from 17 percent, ahead of the October 27 election.

Voters instead look set to choose either poet and former culture minister Michael D. Higgins or openly gay senator David Norris, a scholar in the works of novelist James Joyce, for the largely ceremonial role.

Higgins has the support of 27 percent and Norris 20 percent of voters, the Quantum Research/Sunday Independent poll found.