The 57-year-old is a former judge, prosecutor and defense attorney, and has been one of Barack Obama's advisers. He was also the No. 2 official in the Justice Department under Bill Clinton.
On the last day of Clinton's term, Holder told the White House he was "leaning toward favorable" for a presidential pardon for commodities dealer Marc Rich, who'd spent years running from tax charges. The pardon provoked protests and a congressional investigation over whether it was politically motivated.
Holder later apologized for what he called a snap decision. He said he would have advised against it had he paid more attention.
Holder's nomination could be formally announced as soon as this week.