The White House Chief of Staff has said the delay in nominating a US Ambassador to Ireland does not mean Ireland is not a priority for the Obama administration.

Denis McDonough said Ireland and Northern Ireland remained a fundamental national priority for the US, and a personal one for president Barack Obama.

Missouri lawyer Kevin O'Malley was nominated as the next US Ambassador to Ireland just over two weeks ago.

It is almost 18 months since the previous ambassador Dan Rooney left the post.

Ireland has been without a US Ambassador since December 2012.

Mr McDonough said today that because of this delay, both he and the President were looking forward to his swift confirmation by the Senate.

The White House Chief of Staff did not give a reason for the delay.

He said there was a "thorough nomination process" and the administration was "very serious" about announcing the right candidate in Kevin O'Malley.

Mr McDonough said that it was important to the President that his nominee for Ambassador to Ireland was a "close personal friend" of his.

He said Kevin O'Malley was such a "close personal friend", as the previous ambassador Dan Rooney had been, and that he was also among the "longest supporters" that the President had "enjoyed and relied on for some time".

He also said he had no indication as yet of when Mr O'Malley's Senate confirmation hearing would take place, but that the administration encouraged the Senate to move forward quickly.

Mr McDonough said it would be premature to discuss the policy interests or expectations that the White House had for Kevin O'Malley as Ambassador.

He stressed that the administration attached an importance to and had "a long commitment to Northern Ireland peace and prosperity".

Kevin O'Malley is a widely recognised litigation lawyer, who once trained to be a Catholic priest.

He is very involved in the Irish American and religious community in St Louis where he lives.

Mr O'Malley is of direct Irish descent from both his parents and is said to be proud of his Irish heritage.

He is relatively unknown outside of the Mid-West of the US, and Denis McDonough acknowledged that this was a concern in selecting him as the nominee for Ambassador.   

He said President Barack Obama was "confident that when the Senate confirms him, he'll be an excellent ambassador, reflecting his personal commitment" to the Irish-US relationship.

He said was a leader in his field of law, had been widely publicised and recognised by local and national legal organisations.   

He is a fellow of the American College of Trial Lawyers and consistently listed as one of the best lawyers in America.

He studied to be a priest in a Catholic seminary and is a leading supporter of the Catholic Student Centre at Washington University in St Louis.  

Mr McDonough said today that this meant Kevin O'Malley would bring a "strong understanding of the cultural importance of religion in Ireland".

He said Mr O'Malley had dedicated his life to the US and his community both in public and private service.

He was at one time in the Army Reserve and later went on to be a US Attorney.

Mr McDonough said Mr O'Malley had a deep understanding of the political relationship between Ireland and the US, informed by his own Irish heritage.

He said also would bring a strong knowledge to the role of the "religious and cultural underpinnings", and the "very important foreign policy and national security undergirdings" of the relationship between the two countries.

He said he had a strong knowledge of both Irish history and current political dynamics in Ireland.

Before Mr O'Malley officially becomes the next US Ambassador to Ireland, he must got through a Senate confirmation hearing, led by Democratic Senator Robert Menendez of New Jersey.