The Secretary of State for Northern Ireland, Mr Peter Mandelson, was warned on his first visit to Washington there must be no "roll back" in reform of the RUC as set out in the Patten report.
Mr Ben Gilman, the chairman of the Committee on International Relations of the US House of Representatives, told Mr Mandelson "police reform is a touchstone issue" that "goes to the heart of a new Northern Ireland".
There had been strong bi-partisan support from the House leadership in calling for "a major root and branch reform of the RUC", Mr Gilman said in a letter handed over to Mr Mandelson. "I strongly urge that you move forward to implement the Patten report intact without change or cherry-picking."
Mr Gilman said Congress had recently set "some strong preconditions" to future training by the FBI for the RUC or its successor, one of which called for President Clinton to certify that the British and Irish governments were fully committed to implementation of the Patten report.
"Any roll back of the Patten report could create problems here in the Congress in securing FBI and other professional training for Northern Ireland police officers," Mr Gilman's letter says.
Mr Mandelson also had discussions on Northern Ireland with Mr Sandy Berger, the President's national security adviser. He also met Senator Edward Kennedy before leaving for New York.
Asked at a press conference about the likelihood of a visit by President Clinton to Northern Ireland soon, Mr Mandelson said: "I'd love him to come and visit" and "I certainly would give him advice to come, but I don't know his schedule". He had a "fairly comfortable home" in Northern Ireland and would be happy to welcome the President there.
Mr Mandelson said he was asking President Clinton "to bring home to the American business community the huge return they would get for their investment in Northern Ireland". It would be good to see "an economic dividend" for the region under devolution.
He was proud to be the first Secretary of State to be able to announce in Washington that there was now self-government in Northern Ireland.
Asked if the presence of two DUP members in the new Executive could be disruptive as they had described themselves as "ministers in opposition", Mr Mandelson said Mr Peter Robinson and Mr Nigel Dodds were two very able people and "are doing a great job in government in exercising their responsibilities".
He said that "whatever they call themselves, they won't be disruptive of the work of the Executive. I suspect it won't be too long, without putting a time limit on it, when various labels and tags are dropped in the face of the growing reality of their participation in the government of Northern Ireland".