MADRID — Spain's caretaker Prime Minister Pedro Sánchez met with conservative leader Pablo Casado on Monday in his first encounter with opposition politicians in efforts to form a government.

Sánchez's Socialist Party won the April 28 national election, but it fell short of a majority and will need help to stay in power either by forming a coalition government or ruling in minority.

Despite losing more than half its seats, Casado's conservative Popular Party was left as the leading opposition force in parliament.

Casado said after Monday's meeting at the Moncloa presidential palace in Madrid that while his party will not back Sánchez staying in office, it will remain open to agreements for future legislation regarding issues such as pensions, gender-based violence and national security.

Casado said that above all he asked Sánchez to ensure that "the government does not depend on parties that want to fracture Spain," in a reference to the Catalan and Basque separatist parties with national lawmakers that the Socialists could need to reach a majority.

Sánchez tweeted that the talks with Casado were "cordial" and that it "normalized the relationship" between the two rivals after a heated electoral race.

On Tuesday, Sánchez will see the leader of the center-right Citizens party, Albert Rivera, and the leader of the far-left United We Can party, Pablo Iglesias.

All the stakeholders are expected to hold off on striking deals for a government until after May 26 European and local elections.