Taoiseach Bertie Ahern has urged US President George W Bush to look favourably on undocumented Irish people living in America.
Speaking the traditional handing over the shamrock ceremony in the Roosevelt Room of the White House yesterday, Mr Ahern noted the Flight of the Earls - which effectively paved the way for partition - and the settling of Jamestown, Virginia, both in 1607, were being commemorated.
He said the Flight of the Earls, which led the way to the plantation of Ulster, "effectively inaugurated the Irish diaspora"; while 100 years later Irish people began settling in Virginia.
"Each new generation of Irish arriving in this country has made is own contribution and helped assure a unique relationship," Mr Ahern said.
He said more recently arrived Irish have put down "new and deep roots".
With a presidential election next year and a new immigration bill on Capitol Hill, the issue of regularising the status of undocumented Irish - estimated to be as high as 40,000 - is rising up the political agenda.
"The resolution of this issue would mean an enormous amount to so many Irish men and women, and I fervently hope that they will, in the not too distant future, be able to step away from the shadows and into the sunshine of this great country, Mr Ahern said.
In a short speech Mr Bush, who has been guarded on the issue, avoided directly addressing the subject but recognised the historical contribution Irish people have made in areas such as education and construction.
He welcomed the friendship traditionally enjoyed between the two countries and welcomed the "strong and growing trade relationship".
In his address to the small gathering, which included Northern Secretary Peter Hain and Sinn Féin chief negotiator Martin McGuinness, Mr Bush said: "St Patrick's Day is an occasion that unites two distinct groups of Americans: those who are of Irish descent, and those who wish they were."