US President George Bush has nominated Michael Chertoff, a federal appeals judge, as his next secretary of homeland security.
Chertoff was central in shaping the Bush terror strategy
He has played a key part in the Bush administration's "war on terror" strategy, correspondents say.
Ex-police commissioner Bernard Kerik withdrew his name for the post last month because of questions over the immigration status of his housekeeper.
Mr Chertoff's nomination must be approved by the US Senate.
Announcing his choice at the White House, Mr Bush praised his new nominee.
"When Mike is confirmed by the Senate, the Department of Homeland Security will be led by a practical organiser, a skilled manager and a brilliant thinker," he said.
"In the days after 11 September , Mike helped trace the terrorist attacks to the al-Qaeda network. He understood immediately that the strategy in the war on terror is to prevent attacks before they occur," he said.
Mr Chertoff said that, if confirmed, he would "devote all my energy to promoting our homeland security and, as important, to preserving our fundamental liberties".
Mr Chertoff had previously headed the Justice Department's criminal division - from 2001 to 2003 - and played a key role in the legal response to the 11 September attacks, helping to craft the war on terror strategy, says Daniela Relph in Washington.
In the mid-1990s, he was a special counsel for the US Senate's committee that investigated the Whitewater affair involving former President Bill Clinton.
Mr Chertoff has been described as the driving force behind some of the most controversial initiatives in the war on terrorism, our correspondent adds.
Civil liberties groups have accused him of curtailing free speech and the rights of criminal defendants.
Mr Chertoff, 51, is set to replace Tom Ridge, first chief of the Department for Homeland Security, which was created in the wake of the 2001 attacks and is responsible for preventing terror strikes on the US.