Marine Le Pen has sought to purge the FN of associations with her xenophobic, anti-Semitic father.
"I always want my champion to win hands down," Le Pen senior said of Wednesday's debate viewed by more than 16 million people.
But the 88-year-old deemed the duel a "draw", saying his daughter -- who kicked him out of her National Front (FN) party in 2015 -- "perhaps did not rise to the occasion."
Speaking on French radio, he blamed the candidate's advisers for underestimating a "very solid" Macron, wrongly "hoping for a collapse or a psychological meltdown."
A poll by French broadcaster BFMTV found that 63 percent of viewers thought Macron was the "most convincing" of the two, broadly mirroring the forecast result for the decisive election on Sunday.
Marine Le Pen has sought to purge the FN of associations with her xenophobic, anti-Semitic father, who co-founded the party in 1972.
When Le Pen senior was a shock finalist in France's 2002 election, his rival Jacques Chirac refused to debate him out of fear of "normalising hate and intolerance".
He has repeatedly called the Nazi gas chambers a "detail" of history.