To what degree are the problems with the Obamacare website due to sabotage?

I heard an interesting discussion on radio yesterday. (Diane Rehm Show, to be exact)

While there is no doubt that there are real problems with the Obamacare website operations and enrollment mechanism, the journalists suggested that at least some portion of the problems are because anti-ACA people are deliberately trying to overwhelm the site to prevent others from registering.

My personal thought is that there was deliberate sabotage, but not by users (as said on the radio) but by the contractors who built the website infrastructure poorly, on purpose.

I’m certainly not averring that all the problems are deliberately caused, only that some were/are made worse because of intentional human effort.