Even if she does win the presidency, Le Pen would be wise to keep the champagne on ice for a while. She is unlikely to get a majority in the French parliamentary elections, due to be held June 11, and would therefore face a hostile — probably center-right — government standing in the way of executing her plans — and holding a referendum.
Still, she would able to call a nonbinding referendum without the approval of the government.
If the French people were to vote to keep the euro — which is likely if you believe French opinion polls — she would stand down, given then that “70% of my project cannot be put in place.”
Of course, all of these legal considerations regarding EU membership will be of minor importance should France actually decide to leave the eurozone. The economic chaos it would likely cause would be the top priority for everyone in France and across the continent.
The French Central Bank has estimated that refinancing French public debt outside of the eurozone would cost more than 30 billion euros ($32 billion) in additional annual interest.