The Dems probably told him to bow out so they can put a stealth candidate in at the last moment. Yup, I smell a rat.
There is no stealth candidate for them to put in. It's pretty simple. Roberts is polling less than 40% in a three man race. Taylor supporters are not going to go to the Republican, they'll go to Orman. I'm not saying that Roberts is toast, but this isn't going to help him at all.