Far-left contender Jean-Luc Mélenchon won 22 percent of the ballots cast in last week's first round, accounting for more than 7.7 million voters. He has warned his supporters not to help Marine Le Pen, but has stopped short of advising them to vote for Emmanuel Macron.
Mélenchon's France Unbowed party asked members what they intended to do in next Sunday's second round, where incumbent Emmanuel Macron will face far-right hopeful Marine Le Pen.
There were 215,000 participants in the survey. Of that sample, 66 percent said they would either not show up, leave the voting envelope empty, or otherwise spoil their ballot.
The survey did not propose the option of voting for Marine Le Pen.
Thirty-three percent of those who took part said they would vote for Emmanuel Macron.
"The results are not an order to vote for anybody. Voters will make their own choice and vote as they see fit," Mélenchon's campaign team wrote on the party website.
A separate opinion poll at the weekend supports the findings of the France Unbowed party consultation, also revealing that 33 percent of Mélenchon first-round supporters will vote for Emmanuel Macron on Sunday.
Shift from one end of the spectrum to the other
The weekend independent poll also indicates that 16 percent of Mélenchon supporters will shift from one extreme of the political spectrum to the other, giving their second-round vote to Marine Le Pen.
Fifty percent of those questioned refused to answer at all.
Emmanuel Macron has promised to make his next prime minister responsible for ecological planning – a concept popularised by Mélenchon.
- Mélenchon turns kingmaker as Macron and Le Pen pitch for his left-wing votes
- Abstention on the rise as French no longer see voting as a duty
He has also agreed to revise his proposals to make 65 the general retirement age.
Addressing hundreds of supporters in the southern city of Marseille on Saturday, Macron promised a "complete renewal" of his policies.
He said he would also appoint a minister with responsibility for "energy planning" and "a mission to make France the first major industrial nation to end oil, gas and coal consumption".
