Former police commissioner and U.S. homeland security nominee Bernard Kerik (search) said Wednesday he will leave Giuliani Partners, former Mayor Rudolph Giuliani's consulting firm.

At a news conference in Manhattan, Kerik said he had apologized to Giuliani (search) for being a distraction because of his messy withdrawal as a candidate to head the Department of Homeland Security.

The former New York corrections commissioner said he told Giuliani his resignation would be effective immediately. He said he would seek other unspecified business opportunities.

Kerik was nominated by Bush earlier this month to head the Department of Homeland Security (search). He abruptly withdrew his name Dec. 10 after revealing that he had not paid all required taxes for a family nanny-housekeeper and that the woman may have been in the country illegally.

A rash of other scandals soon followed, including allegations that he had connections with people suspected of doing business with the mob and accusations that he had simultaneous extramarital affairs with two women.

Recently, the city Department of Investigation said it had been reviewing Kerik's tenure as police commissioner. According to DOI findings, Kerik submitted a background form when he became commissioner of the Department of Correction in 1998 but did not fill one out when he was appointed police commissioner two years later.