LONDON (AFP) - Mary Lou McDonald will on Saturday (Feb 10) replace Gerry Adams as the president of Sinn Fein following his decision to step down after 34 years as the figurehead of the Irish republican movement.

McDonald, 48, the left-wing party's deputy leader, was confirmed last month as successor to Adams, 69, who has dominated the left-wing party since November 1983.

"I know I have big shoes to fill taking on the role from Gerry Adams, and I know that is impossible," McDonald said.

"But I have brought my own shoes and together, with all of the party membership, we will walk on a journey that will lead to Irish unity.

"We are entering a new era and we can look forward with confidence."

Adams played a major role in convincing the IRA to disarm as part of the Northern Ireland peace process and masterminded Sinn Fein's rise to become the second-biggest political force north of the border and the third in the south.

But many consider his past links to the IRA a millstone, although Adams denies ever being a member of the paramilitary organisation that fought for a unified Ireland.

He told the Press Association on Friday that he regretted blood spilled during Northern Ireland's three-decade long Troubles.

"It took almost from 1976/77 to 1994 before there was the first cessation," he said of the peace process.

"That's an awful long time and a lot of people were killed or injured and traumatised in between." Seen by some as a peacemaker, and by others as a terrorist, Adams said he did not mind what people think of him.

"If I thought about it very deeply those people who detest me will continue to detest me. Those people who admire me will continue to admire me," he said.

Sinn Fein, which wants Northern Ireland to leave the United Kingdom and become part of the Republic of Ireland, is the second-biggest party in the Belfast assembly and the third-biggest in the Dublin parliament.

McDonald has ambitious plans to "see Sinn Fein in government north and south".

Her coronation represents a break from the party's links to the IRA, responsible for more than 1,700 deaths during unrest, and a renewed focus on social issues.

McDonald became a member of the European Parliament in 2004. She was appointed Sinn Fein's deputy leader in 2009 and has represented central Dublin in the Irish parliament since 2011.