European leaders have work to do to convince President Donald Trump of the worth of the EU project, Irish premier Enda Kenny has said.
Mr Kenny will become the first leader from the 27 EU states to remain in the union post-Brexit to meet Mr Trump this week in Washington.
Mr Trump's scheduled meeting with German Chancellor Angela Merkel on Tuesday was postponed until Friday due to snowstorms in the US.
The president has been critical of the EU, suggesting other nations may follow the UK's lead and exit the union.
The Irish Taoiseach, who will meet the president and other senior Republicans on Thursday as part of a St Patrick's Day tradition, said he would highlight the potential mutual benefits of enhanced relations between the US and EU.
"I see Ireland as representative of what it is the European Union can actually contribute to the global development of job opportunities, trade, commerce and development of economies, in the sense that the European Union is not unfriendly to the United States," he said.
"And I accept that we have some work to do in explaining to this administration what it is that the European Union actually stands for, what it is that the European Union does, the opportunities that present themselves by having the four freedoms (movement of goods, people, services and capital between EU states) ... of the European Union which are of enormous potential for the future."
He added: "The potential for further expansion on either side of the Atlantic is enormous between the European Union and the United States."
Mr Kenny will hold bilateral talks with the president in the Oval Office in a day of engagements on Thursday. He will also meet vice president Mike Pence and attend speaker Paul Ryan's annual St Patrick's lunch.
"This is a new administration, it's been a democratic decision by the American people to elect a new president and a new administration, and my responsibility as Taoiseach and leader of our government and in working with my colleagues at a European level is to work with this administration and to make that work in the interests of millions of people on either side of the Atlantic.
"European leaders need to be over here talking to Republicans and Democrats and the administration about what membership of the European Union means and the relationship that it can have with as powerful an entity as the United States.
"It's important that the full story be given here and that it not be just one-sided, so people have a full view of what it is that we stand for - and Ireland is a microcosm of that from a European perspective."
Mr Kenny is also due to raise the issue of securing enhanced rights for the 50,000 Irish "undocumented" who live and work in the US without the required legal permissions.