HARRISBURG, Pa. -

Pollsters say a victory by any Democrat besides Tom Wolf in the primary election for Pennsylvania governor would be shocking.

So far, three polls have shown Wolf leading by at least 20 percentage points, with the most recent one from late April.

Overcoming such a large deficit is certainly possible, but pollsters Terry Madonna of Franklin and Marshall College and Christopher Borick of Muhlenberg College say they can't recall anyone mounting such a dramatic comeback in modern Pennsylvania politics in such a short period of time.

They acknowledge, however, it's more difficult to produce an accurate poll when voter turnout is low.

New polls forthcoming this week could show whether Wolf's popularity have been affected by attack ads in the four-way Democratic primary.

The election is May 20.