The multitude of Republican candidates and the small percentages that separate them shows up in the rapid movement in rank order.
A couple of recent polls have had Dr. Ben Carson ahead or tied with Donald Trump, although Trump leads by six percent in the RealClearPolitics average. Marco Rubio, who has moved up in recent polls, is now in a race for third place with Carly Fiorina.
The message is that the placement of candidates has considerable variation, although there is a discernable top tier with Trump, Carson, Fiorina and Rubio challenging; and a second tier with Bush and Cruz. A third tier barely registering in national polls has Kasich, Huckabee, Christie and Paul hanging on.