The Ulster Unionist Party. Political party of mainstream unionism in Northern Ireland. It represents the majority of Unionists, making it the biggest party in the North, narrowly ahead of the SDLP. It leader is David Trimble. Broadly supported the Good Friday Agreement, although opposition to the deal has increased as the difficulties over IRA decommissioning have continued. The party has links to the Orange Order, although Trimble has recently attempted to reorganise the party's ruling council to remove the Orange block vote.