Right-winger Ms Le Pen, 48, has struggled to regain the initiative after a TV debate in which she came across as angry, vindictive and unclear.
She accepted the debate had been ill-tempered and fiery and suggested her performance mirrored the frustration felt by millions across France.
She said: “My words were nothing but the reflection of the anger that will explode in this country.”
Observers interpreted that as thinly-veiled threat that Mr Macron can expect her to mount an aggressive opposition to his presidency and reform plans should she lose.
Ms Le Pen, who stood down as leader of the far right Front National received a hostile reception at her final campaign stop in Reims cathedral with her ally Nicolas Dupont-Aignan as militants chanted “Marine, give the money back”.
She has refused to answer French investigators questions in a probe into whether she misused European parliamentary funds to pay party members.
Ms Le Pen fired off an angry Tweet afterwards accusing Macron supporters of “violence” and a lack of “dignity” in a sacred place.
If she loses tomorrow, Ms Le Pen still hopes the Front National can win up to 60 new seats in parliament, up from the current two.
Her niece Marion Maréchal-Le Pen said any score above 40 per cent in the run-off would be a “huge victory” and would effectively turn the Front National into the main opposition group.
But the opinion polls suggest that may be wishful thinking with most suggesting Mr Macron, 39, has extended his lead by up to four percentage points since Wednesday.
Mr Macron said he was confident French voters would convert a presidential win into a parliamentary majority next month, without which he risks becoming a lame duck hamstrung by a government of cohabitation.
The candidates of France’s two mainstream parties, the Socialists and centre-Right Républicains , crashed out of the presidential race in round one.