"Politics is the mind-killer" is still true as ever, and I fear that the linked article may be suffering from this. For instance, breathless statements like:

After replacing condescension with conversation, the left could then present a plan that was actionable and concrete. Instead of trying to square the circle by promising to keep the settlements and bring peace and maintain security and foster goodwill all at the same time, it should be blunt about what it really believes.

seem to imply a kind of 'us vs. them' mentality where the left is a coherent body with a uniform set of beliefs. And statements lacking evidence, like:

They remain unconvinced because they see those ghoulish ISIL videos and they know that it’s only a matter of time before the turmoil spreading everywhere from Libya to Syria knocks at their door.

presume voter intentions and have no basis in what is known about ISIS. The article is mostly statements like this, so I won't bother quoting all of them.

There are plenty of good, rational, evidence-based articles on movements of public opinion. I'm curious as to why you decided to link this one instead.