The family of murdered Belfast man Robert McCartney are in the United States this week as part of their high profile campaign for justice.
The McCartney sisters have already met Senator Ted Kennedy
This is their second visit to the US following their invitation to the White House for Saint Patrick's Day.
Robert McCartney, 33, was murdered in the street outside a bar in Belfast city centre in January.
The sisters, who have already met Senator Ted Kennedy, also plan to hold talks with Senator Hillary Clinton.
Mr McCartney's family have campaigned for justice for their murdered brother and claim they have been intimidated by the IRA.
Catherine McCartney said the family was grateful for the backing they had received from the United States.
"Not just the Bush administration, but other people especially the senators and congress people," she said.
"The only thing that they can do is use what influence they have over Sinn Fein and speak to the British and the Irish governments.
"It's just a matter of keeping the issue there until justice is done."
In March, they had separate meetings with Mr Kennedy and President George Bush, both of whom refused to meet Sinn Fein President Gerry Adams at the time.