Two men identified as radicalized French nationals were arrested in the port city of Marseilles Tuesday morning, according to an NBC News report.
There is an unexpected front-runner in France's presidential race.
The presidential election is being watched as a bellwether for global populist sentiment, in large part because of Le Pen's nationalist, anti-immigration positions.
The French presidential election will kick off on Sunday with its first round, and Last Week Tonight's John Oliver dedicated a lengthy and hilarious segment to the issue, urging the French population to come out and vote, especially in the second round, to avoid a potentially disastrous outcome for the country.
"It's time to put back France in order", she said, using one of her campaign's mantras.
The two men allegedly "intended to commit an attack on French soil in the very short term, which is to say in coming days", Interior Minister Matthias Fekl said during a brief news conference earlier on Tuesday.
Marine Le Pen, the far-right candidate, and Emmanuel Macron, an independent candidate, told Agence France-Presse that their campaigns received warnings about the two men, including their photographs.More news: 21st Century Fox investigating O'Reilly harassment claims
Sarkozy said in a video posted on his Facebook and Twitter accounts that Fillon "has the experience, the will, the project that will enable France to ensure a political change after the five disastrous years we have known".
More than 230 people have been killed in Islamist attacks in France over the last two years, pushing President François Hollande to declare France a nationwide state of emergency.
French Interior Minister Matthias Fekl said the "radicalised" men meant to strike "in the next few days in France", but provided few details about the alleged plot.
With two of the four candidates also hostile to the institutions of the European Union, the result of the May 7 runoff will have far-reaching implications not just for France but for the region as a whole. "Everything will be done to ensure security" for the election, Fekl said.
"It is one of the unknowns of a vote that has many unknowns".
French far right candidate Marine Le Pen is promising a freeze on long-term visas as soon as she takes office, followed by a tax on any company that hires foreign workers. "The campaign must continue until the end".
Referring to the election, Fekl said "every effort" was being made to guard against attacks.