Fears of foreign intervention in Western politics have heightened since the U.S. presidential elections in November.
Polls are tightening, with third-place Francois Fillon picking up support and Macron and Le Pen nearly neck and neck.
Marine Le Pen and Emmanuel Macron will go into Monday's first French presidential debate as clear frontrunners.
The current state of high alert has been in place since 2015, after 130 were killed in Paris.
Francois Fillon's conservative party apologizes for tweeted image featuring anti-Semitic stereotypes.
The National Front leader called a new cold war with Russia the real threat.
Independent candidate Emmanuel Macron has been bolstered by an alliance with centrist Francois Bayrou.
Both leading candidates for upcoming election in France hold rallies to kick off their candidacy bids
A new poll in "Les Echos" sees the French president third in a variety of scenarios.
The French are shaking off a reputation for stuffy socialism and are promoting tech startups.