Mr Gerry Adams has said there would be little chance of a breakthrough in the peace process during political talks on St Patrick's Day in Washington.
He also said the May 22nd deadline for decommissioning no longer existed. This was strongly denied by Ulster Unionists.
Speaking yesterday in west Belfast, the Sinn Fein president said he was visiting Washington this week "out of a sense of duty".
"It is an occasion for us to brief people on the ongoing situation, thank people - from the President down and right through Irish America - and ask them to continue their efforts to see political stability and political institutions and implementation of the Good Friday agreement," he said.
"I don't see there being any breakthroughs in the States, but it is an opportunity to thank friends and try to win new friends."
Asked why he believed the May 22nd deadline no longer existed, Mr Adams said: "Because those who have made the government and the rights and entitlements of voters conditional upon armed groups decommissioning their weapons, and to do so in a certain way, in certain conditions and by a certain time, have totally and absolutely confused and subverted the entire process."
He said it was time the British and Irish governments "got their act in order".
"I support the calls of the Irish Government for there to be demilitarisation, but we have an Irish Government statement one day and a British government statement on another, contradicting one another," he said.
An Ulster Unionist MLA, Mr Michael McGimpsey, described Mr Adams's comments on the deadline as ridiculous.
"It was the only firm date agreed by all participants who signed up to the agreement," he said.
"It is the IRA who failed to honour the clear understanding that was reached in the Mitchell review and it is the IRA who are now failing to honour the date of May 22nd.
"If the IRA is abandoning this important date, then they must be abandoning their support for the agreement."