Sources say Press Undersecretary Michael Toledo, a lawyer like Puno, is likely to succeed the press secretary.
While Puno still does not belong to any political party, he has indicated he may join President Estradas Partido ng Masang Pilipino (PMP) before he officially files his certificate of candidacy by January.
Mr. Estrada confirmed earlier that Puno and several other Cabinet members will resign to run for office in the May 2001 polls.
Asked if there will be a Cabinet revamp next month, the President replied: "Maybe, because many are running in the elections like Puno and others. So there might be a reshuffle."
Puno said he still has until Jan. 2-14 next year to truly make up his mind. That period represents the time span for the filing of certificates of candidacy, during which time they must also tender their resignations.
"Thats the natural deadline for us," Puno said.
Other Cabinet secretaries expected to run in the May polls are Executive Secretary Ronaldo Zamora, Interior and Local Government Secretary Alfredo Lim, Defense Secretary Orlando Mercado and Agriculture Secretary Edgardo Angara.
Zamora said his bid for the lone congressional seat in his hometown of San Juan is in the "realm of speculation."
The executive secretary is being pushed by his partymates at the Lapian ng Masang Pilipino (LAMP) to run for the speakership of the House of Representatives in order for the ruling coalition to reassert its majority in the House. Marichu Villanueva