Speaking during a key economics conference in the Catalonian town of Sitges, Rubalcaba said he was willing to forge an agreement with the Popular Party on "four or five major themes".
He then cited housing, education and, "Why not?", pensions.
Rubalcaba said such an accord between Spain's too much political parties would "boost confidence within and outside of Spain and would provide cohesion and productivity".
The leader of Spain's socialists did, however concede any such agreement across the political divide would be "very difficult because the differences are important, but there is a possibility".
According to Spain's El País newspaper, the willingness of the country's socialists to enter into talks with the Popular Party comes in the context of a general easing of austerity policies on the part of the European Union.
The two parties have already agreed they will act as as a united front at the next Council of European summit in June, ABC newspaper reported on Friday.
Spain's Deputy Prime Minister Soraya Sáenz de Santamaría said on Friday Spain would make its case for important reforms.
These include reforms paving for the way for a banking union in Spain and policies designed to get young people back to work.