A conservative has been sworn in as the new mayor of Madrid in the first major political shift enabled by the far-right's gains in last month's Spanish local and regional elections.

The Popular Party's José Luis Martínez-Almeida replaces the far-left administration led by former judge Manuela Carmena. He will govern Madrid in coalition with the center-right Citizens' party and with the backing of Vox's national-populists.

Reliance on Vox for post-electoral pacts is earning Citizens strong criticism from within its own ranks and even from French President Emmanuel Macron.

In Barcelona, far-left mayor Ada Colau is set to be re-elected later Saturday, with the help of the Socialists and of a group led by former French Prime Minister Manuel Valls, who has refused to work with Vox.