The family of Joseph Rafferty, who was murdered in Dublin last April, is to travel to the US next month to meet a number of senators including Ted Kennedy, Hillary Clinton and John McCain.
The family believe there was IRA involvement in his killing.
The dead man's family will spend five days in New York and Washington. As well as meeting the three senators, they have also arranged talks with the US special envoy for Northern Ireland, Mitchell Reiss.
Mr Rafferty's family has made a request to meet President Bush but has not yet received a response from the White House. They are due to travel on February 4th.
Mr Rafferty's sister, Esther Uzell, said she was hopeful the visit would result in pressure in the US on Sinn Féin, who she believes can greatly assist gardaí in their investigation into her brother's murder.
"We're hoping it will pressurise them into handing up the murderer. The McCartney sisters managed to get a lot of publicity from their trip to the US.
"Up to that point, Sinn Féin had a policy of denying any responsibility by the republican movement in the murder of Robert McCartney, but that changed after the US visit."
Ms Uzell will be accompanied by her sister, Sandra, and her brother-in-law, Bart Little. Cllr Gary Keegan (FF), who has helped the family with its Justice for Joe campaign, will also travel.
The trip was first mooted last November when Ms Uzell met in Dublin with US ambassador James C Kenny. However, plans to travel that month were put on hold to allow time to organise meetings.
Mr Rafferty, a 29-year-old father of one, was shot dead last April in the Ongar housing estate in west Dublin where he lived. He was originally from the south inner city. In the months leading to his murder he had become embroiled in a dispute with a family from that area.
Mr Rafferty was told a number of times by members of the family he had clashed with that he would be "got" by the IRA. The woman whose sons he had become embroiled with is in a relationship with a former member of the IRA. The man has also worked on Sinn Féin election campaigns. He is the only suspect in the murder.
Ms Uzell believes that because of the suspect's association with Sinn Féin/IRA, the republican movement has a responsibility to help bring him to justice.
