An Ifop-Fiducial survey showed Le Pen at the top of voter intentions in the first round with 26 to 26.5 percent, depending on who wins the left party ticket in the due primary.
With 24 to 25 percent of votes, Fillon, the former conservative party prime minister, is seen losing his lead in the first round. However, he will largely beat Le Pen with 64 percent to 36 percent in a runoff next May, the poll added.
According to the survey, independent candidate Emmanuel Macron is gaining momentum with 17 to 20 percent of the vote in the first round, up by three points from December.
If he makes it to the second round against the front-runner Fillon, Macron will collect 52 percent of the vote against Fillon's 48 percent.
Ifop-Fiducial conducted its poll between Jan. 3 and 6, questioning 1,860 registered voters.