Mexico's interior secretary says he is resigning to start his campaign for the presidency in the 2006 election.
Santiago Creel said Wednesday he will seek the nomination of President Vicente Fox's National Action Party. President Fox is barred by Mexican law from seeking another term.
A presidential spokesman says Mr. Creel's replacement will be announced on Thursday.
Polls show Mr. Creel is a favorite to win his party's nomination, but still trails candidates from rival parties, including Mexico City Mayor Andres Manuel Lopez Obrador. Mr. Lopez Obrador defeated Mr. Creel in the Mexico City mayoral race in 2000.
Mr. Lopez Obrador has announced plans to resign his position in July so he can focus on campaigning for the presidency.
Some information for this report provided by Reuters and AP.