"It is difficult to understand where these rumors come from. I’ve already expressed my position: clearly and definitely not," Juppe told journalists, as quoted by Le Parisien newspaper.
Juppe reiterated his statement on Twitter, where he wrote that "a no is a no."
Aux auteurs de rumeurs infondées, une confirmation: pour moi, NON c'est NON. Je dirai pourquoi. Aujourd'hui écoutons FF, notre candidat.
— Alain Juppé (@alainjuppe) February 6, 2017
In November 2016, Fillon defeated Juppe in the second round of the center-right primaries, receiving over 4.1 million of votes.
Fillon, who was initially one of the pollsters' favorites, saw his ratings drop after the scandal broke out in late January around his wife allegedly having been paid from state funds for jobs without exercising her duties. French media also questioned Fillon's children's employment as his parliamentary assistants between 2005 and 2007.
The center-right candidate has denied all accusations and pledged to continue fighting. On Sunday, a poll by Ifop revealed that as many as 68 percent of French respondents believe that Fillon should step down as a presidential candidate.
The first round of the French presidential elections is scheduled for April 23, with the run-off slated for May 7.