PARIS—Far-right French presidential candidate Marine Le Pen heightened her rhetoric against global finance on Monday in an effort to rally leftist voters as the National Front leader continues to trail her rivalEmmanuel Macron in polls.

With less than a week to go until Sunday’s runoff, Ms. Le Pen used a rally in northern Paris to paint Mr. Macron, a former investment banker, as a proxy for a “wild globalization” of the sort that has been widely rejected by French left-wing voters.

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