Controversy over the release of Lockerbie bomber Abdelbaset al-Megrahi is set to overshadow David Cameron's first official visit to Washington DC.
The prime minister's trip for talks with US president Barack Obama tomorrow will be framed around discussions about the ongoing struggle in Afghanistan and energy giant BP's efforts to end the Gulf of Mexico oil spill disaster.
But as a result of the latter popular anger in America is growing against BP relating to its alleged involvement in the release of Abdelbaset al-Megrahi, the only man convicted of the 1988 Lockerbie bombing in which 270 people died.
"No matter how powerful the corporation, how important the foreign government, a blood money deal is a blood money deal," Democratic senator Chuck Schumer was quoted by the New York Daily News as saying.
"BP wanted access to Libya's oil fields. Libya wanted Megrahi back. This hardly seems like a coincidence."
Allegations that BP intervened in a bid to protect its lucrative oil deal with the Libyan regime were rejected by foreign secretary William Hague at the weekend.
The issue is being probed by the US Senate's foreign relations committee, which has received a letter from Mr Hague assuring him of the present UK government's opposition to Megrahi's release.
"I know there has been much speculation over the connection between the conversations the previous British government had with BP over their interests in Libya, and the Scottish decision to release Megrahi," the foreign secretary wrote.
"There is no evidence that corroborates in any way the allegations of BP involvement in the Scottish executive's decision to release Megrahi on compassionate grounds in 2009, nor any suggestion that the Scottish executive decided to release Megrahi in order to facilitate oil deals for BP."
Megrahi had served eight years of a 27-year sentence after being convicted in 2001.
Meanwhile the first visit by Mr Cameron to the White House is refocusing attention on the US-UK special relationship.
"Cameron has struck just the right tone in saying that the relationship with the US should be close, but not special," Britain's former ambassador in Washington, Christopher Meyer, wrote in the Mail newspaper.
He added: "If ever there was a moment for Britain to press the reset button, it is in its relationship with America. That should be David Cameron's paramount objective."