If the National Rally does secure an absolute majority, the French leader could find himself forced into a difficult "cohabitation" with the country's first far-right government since the Second World War.
But her hopes of a majority in the National Assembly seem less certain after centrist and left-wing candidates pulled out of races to boost the chances of their moderate rivals to block the far-right.
The voting taking place on Sunday will determine who is prime minister but not president, with Mr Macron already set on remaining in his role until the end of his term in 2027.
If Ms Le Pen's party wins an absolute majority, France would have a government and president from opposing political camps for only the fourth time in post-war history.
The president is weakened at home during cohabitation, but still holds some powers over foreign policy, European affairs and defence and is in charge of negotiating and ratifying international treaties.
A hung parliament and the need to build cross-party consensus to agree on government positions and legislation would be challenging given France's fractious politics and deep divisions over taxes, immigration and Middle East policy.
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