Act Party founder Sir Roger Douglas has sounded a warning against former MP Rodney Hide returning to the party leadership.
Sir Roger says the party needs younger leaders.
John Banks is to stand down as leader in February, and a strong camp within Act favours the return of Mr Hide, who was ousted in a 2011 leadership coup supported by Sir Roger.
Sir Roger made his attacks on Mr Hide in a statement but without naming him.
He said that former members of Act had left in their droves because of the ''populist approach adopted by one or two of its leading members" and they needed to be welcomed back into the fold.
Mr Hide's populist approach was known to be disliked by Sir Roger to the extent that he returned to Parliament in 2008 in a bid to curb it.
Sir Roger also said the party had to "admit to some serious errors of policies which it promoted in Government, eg, the muddled Auckland City legislation".
Mr Hide was the local government minister who shepherded that legislation through Parliament.
Sir Roger said a new party to fill the void left by Act would be unnecessary if the party returned immediately to its founding principles and "announces a new, younger leadership team".
"I recommend that Act gets real and like thousands of other once-active old members, stand ready to help in the background if Act decides to move forward with a new, young generation, rather than a return to a dubious past."
Sir Roger's statement to the Herald was ostensibly to comment on a Herald editorial of December 6.
But it was clearly a response to an article in yesterday's Herald which revealed that former National leader Don Brash, the man who had ousted Mr Hide as leader in 2011, had recently tried to persuade Mr Hide to return.
Mr Hide was the MP for Epsom and Dr Brash persuaded the Act board to support former National minister John Banks as Act's Epsom candidate.
Mr Banks, who is facing electoral charges, says he will not contest Epsom again.