PSD and PS in the Portuguese polls

So few polls have been conducted in the more than 6 months since the general election in Portugal that one has to feel discomfort in analyzing them. And yet, two things seem relatively clear: in spite of dramatic austerity policies, PSD retains lead; and in spite of retaining lead, such lead is clearly diminishing. I guess you can take this and spin it as you prefer.

Data taken from here.