It was not a campaign promise. This was said after he was President as he was explaining legislation:
It was the 2013 lie of the year:
Obama's 'You Can Keep It' Promise Is 'Lie Of The Year'
This was long after he was elected to a second term
Be careful how you call people liars. Some could say the same about your statement that it was a campaign promise when in reality it was much more. As for Trump, I think most of the things he says are due to his not knowing the facts as opposed to out and out lying. I would say the same about you in this example.