I think race will tighten- here's why?

RK

But October may see the end of Obama's surge: He's peaking too soon.
Once the Democrat is seen as the clear leader and likely winner, the spotlight will inevitably shift to him. And he may not benefit from the increased attention.
Obama didn't do well when he last emerged on top, in later Democratic primaries. The more it appeared that Hillary Clintonwould lose, the more voter concerns over Obama's relationship with the Rev. Jeremiah Wright cost him state after state in the later primaries.

They will examine his tax proposals and spending plans, and question his close ties with shady, even violent characters
October usually full of surprises!