In the UMP’s first-ever primary, Kosciusko-Morizet won a convincing 58 per cent in the first round, despite the opposition of anti-gay marriage campaigners and a row over the running of the electronic vote.
She will lead a list of party candidates in the 2014 municipal elections, the next big electoral test that France’s political parties are to face.
The UMP, which is still trying to recover from a divisive contest over the party leadership that followed Nicolas Sarkozy’s defeat in the 2012 presidential election, hopes to profit from disillusion with François Hollande’s Socialist-led government.
“More and more French people really want to issue a warning to François Hollande” and his policies, said the winner of the UMP leadership vote, Jean-François Copé.
For her part Kosciusko-Morizet haled a “wind of liberty that goes so well with Paris and its history” after the result was announced.
Hidalgo, who has already been chosen to head the Socialists’ list, on Tuesday jeered that she "understands" that her rival will wish to dissociate the UMP from the corruption cases that have arisen from the right’s years of control of the capital.
She was proud to defend the record of current mayor Betrand Delanoë, who is not standing again, she said.
Several other parties, apart from the UMP and the Socialists, will stand in the municipal elections.
They will include the far-right Front National, the Greens, who are in local and national coalition with the Socialists, and Jean-Luc Mélenchon’s Left Front but none are likely to come out ahead of the big two parties.