MINISTER for Enterprise, Trade and Employment Micheal Martin began a weeklong trade mission in the U.S. on Monday. Martin, who will be meeting with heads from various U.S. companies in an effort to promote Ireland as a place of investment, said ahead of his visit that he would be using the Irish membership of the European Union as a selling point. Martin said in a statement that Ireland's economic interests of the future would be served better with a yes vote in the upcoming referendum on the EU's Lisbon Reform Treaty. He said a no vote would lead to a reduction in the level of foreign investment from the U.S.Martin was in California recently leading an Enterprise Ireland trade mission where 100 Irish companies secured ?29 million in new contracts during the visit. In the last year Irish companies have opened 47 offices at various locations in the U.S.Outgoing Taoiseach (Prime Minister) Bertie Ahern will arrive in Washington D.C. on Tuesday, April 29 in preparation for his address to a Joint Session of Congress on Wednesday, April 30. Ahern, who will step down as taoiseach on May 6, when current Finance Minister Brian Cowen will take his place, is expected to attend a reception at the residence of the Irish Ambassador to the U.S. Michael Collins that evening. On Thursday, Ahern will fly to Boston where he will deliver a speech on the EU at Harvard University. He is to depart Boston and fly back to Ireland on Friday, May 2. Back in February and prior to announcing his resignation as Taoiseach, Ahern accepted the invitation saying it was an "honor for Ireland and one of great historic significance, reflecting the unique friendship between Ireland and the United States over many centuries and which continues to the present day."