"The European Union will die because the people do not want it anymore ... arrogant and hegemonic empires are destined to perish," Le Pen said at a Sunday rally following her recent visit to Russia, Reuters reports.
"The time has come to defeat globalists," she said.
Opinion polls forecast that Le Pen will do well in the April 23 first round of the presidential election only to lose the May 7 run-off to Macron.
But the high number of undecided voters means the outcome remains unpredictable and motivating people to go to the polling stations will be key for the top candidates.
Read alsoMacron on top after first presidential debate of French race - BloombergIts opposition to the EU and the euro currency underlines an anti-establishment stance that pleases the National Front's grassroots supporters and attracts voters angry with globalization.
Reacting to Le Pen's comments on the death of the EU, France's ambassador to the United States, Gerard Araud, tweeted: "That'll be the real significance of the French elections: the survival or the demise of the EU. A quasi-referendum."
Some 72% of French voters want to keep the euro, an Ifop poll published in Le Figaro newspaper showed.
But unlike voters overall, a large majority of National Front voters back a euro exit, the poll showed.