Last week's primaries to lead the conservative PP party saw two of the six candidates make it to the next round.
Delegates at a party conference on 20-21 July will choose between María Soraya Sáenz de Santamaría, seen as close to the politics of fomer leader, Mariano Rajoy, and Pablo Casado, closer to the right wing of the party.
Despite their differences, both were in good spirits at a dinner on Tuesday.
The election process follows accounts of widespread corruption within PP, as its position as the country's leading party became untenable.
A new leader is set to be chosen before the end of July.