Former President Bakili Muluzi has apologised to Malawians for choosing a successor who has turned against him.
Ex-President Bakili Muluzi remains a powerful figure
Current President Bingu wa Mutharika was proposed by Mr Muluzi as the United Democratic Front candidate in the 2004 presidential elections.
But he resigned from the UDF after a bitter political tussle and is now launching his own political party.
President Mutharika accuses Mr Muluzi of thwarting his high-profile anti-corruption campaign.
"Let me apologise to the country for the choice of Bingu wa Mutharika and imposing him on the country," Mr Muluzi told a political rally in the capital, Lilongwe.
Bingu wa Mutharika has proved to be no puppet of his predecessor
"I didn't know he would be accommodating dissenting views," he said.
Mr Muluzi, who remains extremely influential within the UDF, chose Mr Mutharika as presidential candidate after parliament rejected his attempt to amend the constitution to allow him to stand for a third term.
The BBC's Raphael Tenthani says it is the first time Mr Muluzi has admitted imposing a successor on his party and suggests the gloves have now come off in their worsening row.
No party has a majority in the 193-member parliament, but the UDF is believed to be considering impeaching the president.