The Taoiseach has left for a five-day visit to the US, culminating in the traditional presentation of a bowl of shamrock to the US President, George W Bush, on Friday.

Bertie Ahern will also visit San Jose in California for a number of trade related engagements, and to mark the 20th anniversary of the city's twinning with Dublin.

The St Patrick's Day celebrations in the White House have now become an established tradition, giving Irish politicians access to the very highest level of the US political system.

Ian Paisley of the DUP has turned down his invitation to the event on Friday, although the leaders of Northern Ireland's four other main parties will be attending.

Northern Ireland will be less prominent as an issue this year - the main political focus will be on efforts to help illegal Irish immigrants in the US.

The Taoiseach will be encouraging those efforts in his meeting with Mr Bush, and in a series of events on Capitol Hill on Thursday.

The first part of his visit will be to San Jose in California, which was twinned with Dublin two decades ago when Mr Ahern was Lord Mayor.

He will be meeting a number of business leaders from Silicon Valley, with the aim of strengthening links with the Irish economy.