Emphasis added.
Lots of former Ds eventually wised up and became Rs. Some (Ronald Reagan, Rick Perry, Michelle Bachman, Herman Cain) did generally well as Rs, others (Michael Bloomberg) not so much.
Also, Ben Nighthorse Campbell from CO, D>R.
It is generally assumed that Bloomberg only switched parties to circumvent New York City's Mayoral term limit requirements, not for any change of heart in policies. That's the general assumption, which can be challenged, but I find it more than a little believable.