A manchurian candidate tries to destroy things from the inside out, as a double agent... Committing espionage, and is a traitor. That would be a definition easy enough to ascribe to BHO, and rather difficult to ascribe to MR. What you describe is a hypocrite. Which is just as easy to ascribe to BHO as many politicians, from both sides of the aisle.
I claim that Romney would have destroyed things from the inside out as the POTUS. He would have destroyed the middle class. He would have made the poor poorer. He would have increased military spending to protect more FOREIGNERS and MUSLIMS and build FOREIGN nations while reducing food stamp outlays to U.S. citizens If that's not a definition of a Manchurian candidate, then I don't know what is.