when a hung parliament was returned after last june 's elections , the 17 representatives of catalonia 's covergencia i unio -lrb- ciu -rrb- group in parliament and the five members of the basque nationalist party -lrb- pnv -rrb- joined forces with the 159 socialist deputies to ensure the necessary majority in the 350 -member legislature for mr gonzalez 's investiture as prime minister for a fourth term .