Far-right leader Marine Le Pen told supporters Tuesday that she will support neither incumbent President Nicolas Sarkozy, nor challenger, socialist Francois Hollande, in Sunday's French presidential runoff election.

In a speech at her National Front party's traditional May 1 march, Le Pen said she will cast a blank ballot in protest. Although she said it is up to her supporters to make their own decision, she suggested they do the same.

Le Pen's anti-immigration party garnered a surprising 18-percent score in the April 22 first-round vote, making the support of her followers key for Sunday's runoff.

Mr. Sarkozy is trailing Mr. Hollande in opinion polls. Mr. Hollande emerged as the frontrunner in the first-round vote, edging the incumbent.