Sorry, I must have missed it. What has Obama done that was a violation of the constitution?
Technically speaking, you can get him for a few things. He delayed some of the Obamacare stuff which was already passed as law. It is just funny that the side which voted unanimously against it, is all of a sudden, in favor of enforcing it. Rings hollow to me.
More to the point, you could get him for expanded use of drones (especially on US citizens) as well as expanding war powers of the President. Specifically, you could make the argument that he broke it with Libya, although it is a bit of a gray area. Maybe recess appointments but everyone does those.
Also a number of other issues like NSA gathering and the like that he didn't necessarily do but hasn't done much of anything to curb either.
Problem is that most of this is terrorism related so it is tough to compare with other presidents. The only comparison is Bush and it isn't pretty either. He did recess appointments. He started much of the NSA programs with the Patriot Act. Similarly, Bush used the AUMF. Also have the whole torture thing which could be tried under our Constitution or at the very least, a war crime.
Lastly, Bush delayed the implementation of Medicare Part D b/c he also realized how it wasn't ready and nobody seemed to care.
So most of this is just partisan crap and the rest is unfortunately the new normal. I can't take many Conservatives seriously b/c they were quiet 8+ years ago.