WASHINGTON, Dec 11: President Bush's choice to head the US Department of Homeland Security, Bernard Kerik, has unexpectedly withdrawn his name from consideration.

The White House announced his withdrawal in a two-sentence e-mail sent to media outlets on Friday night, but did not give any cause beyond saying that Mr Kerik "is withdrawing his name for personal reasons".

On Saturday, the media received copies of the letter Mr Kerik had sent to Mr Bush. "While I will always consider your confidence in me to be the honor of a lifetime," Mr Kerik said in the one-page letter, "I am convinced that, for personal reasons, moving forward would not be in the best interests of your administration, the Department of Homeland Security or the American people."

Mr Kerik blamed "matters personal to me" as the reason for his withdrawal and, in his letter, apologized personally to the president for not focusing on them earlier.

The announcement caught the Bush administration by surprise, but White House spokesman Scott McClellan said the president would "move as quickly as we can to name someone else to fill the position". Several administration favorites, including former New York City Mayor Rudolph W. Giuliani, were on the shortlist when Mr Kerik was named.

In recent days, Democrats and a number of news organizations have raised questions about Mr Kerik's ties to Taser International, an Arizona-based manufacturer of stun guns. Mr Kerik earned millions from the company by promoting the sale of Tasers to law-enforcement agencies, mainly the Department of Homeland Security.

On Friday, outgoing Homeland Security chief Tom Ridge said Mr Kerik went through a "rigorous process of filling out disclosure forms" after being tapped for the job.

Mr Kerik said during this process he discovered "information that now leads me to question the immigration status of a person who had been in my employ as a housekeeper and nanny".

"It has also been brought to my attention that for a period of time during such employment required payments and related (tax) filings had not been made," he wrote.

Mr Kerik's so-called "nanny problem" led to the withdrawal of three cabinet nominations during the Clinton era.