I think Obama has run into the same issue all Presidents run into; they make campaign statements that are based on an outside view off the circumstances, then once they enter the White House, well, we see the results with every newly elected President v. campain "promises" or speeches.
He appears to have thought he was going to be able to do certain things that are not as easily deconstructed once they are established. A few examples: The Patriot Act, Guantamino Bay, Iraq war.
Once power is given over to the government--through The Patriot Act--historically, it seems the government tends to put up a fight when it is demanded by the public to back away from the powers given. The Patriot Act was a knee-jerk reaction that Americans are going to pay for many years by having their rights infringed upon.
All politicians have ideas of what they are going to do while in office, most of those things are not followed through with because of the social mood, politics, etc.