Minister Brigitte Bourguignon faces the candidate of the National Rally in Pas-de-Calais, while in Paris, it is a duel on the left which is played between the rebellious Danielle Simonnet and the socialist Lamia El Aaraje, who came in first in the first round.
Four partial legislative elections take place on Sunday in the departments of Pas-de-Calais, Oise, Paris and Indre-et-Loire.
Attention is particularly focused on the 15th district of Paris, in the 20th arrondissement of the capital, and the 6th district of Pas-de-Calais.
Europe 1 takes stock of the issues.
An LREM / RN duel in Pas-de-Calais
This will perhaps be the first partial legislative victory for La République en Marche, which has suffered only failures since the start of the five-year term.
In the 6th district of Pas-de-Calais, Minister Brigitte Bourguignon came out on top in the first round, with nearly 35% of the vote.
In front of her, the candidate of the National Rally: Marie-Christine Bourgeois and her 24%.
La Marcheuse benefits from the implicit support of Xavier Bertrand, who from Sunday evening called to block the far right.
The former LR, president of Hauts-de-France, is himself neck and neck with the RN for the regional.
>>
Find Europe morning weekend in podcast and replay here
In Paris, a clash that illustrates the dissensions on the left
In Paris, it's another match that is played in the 20th: a kind of primary on the left.
Arriving first in the first round with nearly 26% of the vote, the PS candidate Lamia El Aaraje faces the rebellious Danielle Simonnet who won nearly 21% of the votes.
Here, no help from the other candidates. The green candidate trusts the "free will" of voters. The Communists, also eliminated, are not unanimous. A new illustration of the tensions on the left, where it is never easy to line up all behind the same candidate.