"I have to resign because I will run for a seat in the House of Representatives," he told DOJ employees.
Datumanong, who will file his certificate of candidacy on Dec. 29, said he wants to give President Arroyo time to pick his replacement.
"I have not yet recommended anybody," he said. "And I am also not aware as to who are those being considered to be the next justice secretary."
Datumanong refused to say if one of his two undersecretaries — Merceditas Gutierrez and Jose Calida — would be named to replace him.
However, the names of Deputy Speaker for the Visayas Raul Gonzalez and retired Supreme Court justice Josue Bellosillo have been floated as Datumanong’s possible successor.
Presidential Spokesman Ignacio Bunye said the Palace search committee has prepared a "short list" of nominees for secretary of justice.
"The short list is now being reviewed by the selection committee," he said.
The President will choose Datumanong’s successor from among those in the "short list," he added.
However, Bunye said he had not yet seen a copy of the "short list" so that he does not know who are being considered for the post of justice secretary.
"We’ll just make the announcement as soon as the selection is actually been made by the President," he said.
Bunye said apart from Datumanong, no Cabinet secretary had yet announced plans to resign and run in next May’s elections.
Trade and Industry Secretary Manuel Roxas II was the first to resign last Dec. 10 to prepare for his candidacy for the Senate, he added.
At the Department of Health, Dr. Enrique Domingo has resigned as assistant secretary for public health to run as congressman of Pampanga’s third district.
Domingo’s resignation will take effect on Dec. 30.
Meanwhile, Housing Secretary Michael Defensor, Mrs. Arroyo’s campaign spokesman, said several Cabinet members have not yet abandoned their plans to run for public office next year.
Defensor mentioned the vice presidential bids of Tourism Secretary Richard Gordon, and Chairman Bayani Fernando of the Metro Manila Development Authority.
Agrarian Reform Secretary Roberto Pagdanganan has also intimated his desire to seek a Senate seat, he added. — With reports from Marichu Villanueva, Sheila Crisostomo