Compare the visuals of the Donald Trump endorsement with Governor Chris Christie's endorsement of Governor Romney.
In the Christie endorsement, Romney is definitely in charge and introduces Christie who stands humbly to the side awaiting his turn to speak.
In the Trump endorsement, Romney and wife Ann stand hand in hand patiently awaiting Trump's endorsement. Trump is in charge and introduces Romney.
Unlike with Governor Christie, the visuals are that Romney needs Trump. Not a good visual for someone who wants to hold the most powerful position in the world-- president of the United States.