Senator Edward Kennedy is expected to reaffirm the US government's support for the peace process during a series of engagements in Derry today.
Mr Kennedy will urge all participants to stay with the process in his Tip O'Neill memorial lecture in the Guildhall this morning, a member of the senator's advance party said.
Mr Kennedy will have lunch with local civic dignitaries and representatives of the University of Ulster and is expected to meet representatives of nationalist and unionist community groups, including the Bloody Sunday Trust and the Apprentice Boys of Derry.
Mr Kennedy is expected to take a brief walk on the city's walls, and then visit the Protestant Fountain estate. He will also visit the Church of Ireland's diocesan hall in London Street.