"I will ask for parliament's confidence to form a progressive government," Sanchez said in a address to the legislators of his Socialist Party.
He said his party, which won the second-highest number of votes in the general election held last month, will first seek to clinch the lower house speaker position on Thursday.
Sanchez, who first took power in 2018, has ruled since early 2020 thanks to a minority coalition with a far-left party.
The conservative People's Party won more seats than the Socialists, but did not secure an outright majority and faces an uphill battle as it so far lacks enough support to form a government, as does Sanchez.
Reporting by Inti Landauro, editing by Andrei Khalip; Editing by Sharon SingletonOur Standards: The Thomson Reuters Trust Principles.
Persons:
Pedro Sanchez, Violeta Santos Moura, Sanchez, Inti Landauro, Andrei Khalip, Sharon Singleton
Organizations:
Spain's, Socialist Party, PSOE, Rights, People's Party, Socialists, Thomson
Locations:
Getafe, Spain