Sinn Féin president Gerry Adams has launched his party's Assembly election campaign in Belfast and pledged that he will work to further the political process in defiance of "unrepresentative groups".
The party had considered postponement of the campaign following the murder of Constable Ronan Kerr. But Mr Adams said the political process "cannot become a hostage" to dissident gangs.
"We stand here determined to keep making politics work. To keep defending the political institutions and keep delivering for ordinary people and demonstrating what true republicanism is about," he said.
Sinn Féin is running 40 candidates across all 18 Northern Assembly constituencies and hoping to build on the 28 seats it won in the 2007 election.
Mr Adams - surrounded by candidates, outgoing Assembly members and TDs - said his party must stand by the Good Friday agreement and its institutions.
Mindful of the relatives of Ronan Kerr, Mr Adams said that Deputy First Minister Martin McGuinness and First Minister Peter Robinson "spoke for all of us over the weekend when the extended to the Kerr family our solidarity and support".
Turning to Sinn Féin's Assembly record since the last election four years ago, Mr Adams said his party had delivered on its promise of political change, progress towards Irish unity and practical help for the electorate.
"We pledged to continue to be bold and decisive, to stand up for ourselves by standing up to the [British and Irish] governments and to those opposed to change," he said.
"We asked for your vote as an endorsement of our peace strategy. We asked for your vote to build a dynamic for change throughout Ireland. We asked for your vote to help us shape the future in the way that you want, in the way that benefits all and in a way that builds the Ireland of Equals to which we aspire," he added.
Sinn Féin's Executive ministers had delivered in areas from agriculture, to water charges to education, policing and justice, he claimed. The Stormont institutions had delivered for the people of Northern Ireland and would continue to do so after the election.
"Don't let the naysayers tell you that a locally accountable Executive and Assembly haven't made a difference," he said. "They have, and will continue to."
He continued: "Sectarianism remains a major problem which must be confronted. All forms of intolerance are unacceptable. Promoting equality for all is the key. The future lies in Irish unity and national equality."
The party's successes in the last Dáil election showed that the Irish people responded to its calls for equality, fairness and national unity, he added.
"Fourteen Sinn Féin TDs were elected to Leinster House, the largest number since partition 90 years ago. Sinn Féin is an all-Ireland party. We are the only all-Ireland party. We are now in a position to effect significant change north and south and we are committed to doing so."
The party manifesto is to be released later in the campaign.
In answer to questions, Mr Adams endorsed Martin McGuinness's call for support for the PSNI. "Martin is proud of the PSNI and so am I," he said. "We have a duty to stand by them."
Asked if the killers of Ronan Kerr were "traitors" in the same way as Mr McGuinness had branded those dissidents who shot dead Constable Stephen Caroll two years ago, Mr Adams said they were "worse than that".
He also rejected some unionist claims that Sinn Féin had information about dissident groups that had yet to be passed on to the PSNI. "Don't make assumptions that Sinn Féin knows information," Mr Adams said.