Why is Donald Trump so popular?

Donald Trump with Jerry Flynn, Executive Director of the New England Police Benevolent Association, in Portsmouth, New Hampshire. (Photo by Darren McCollester/Getty Images)

A new poll finds Republican voters don't think he is likable.

They don't think he's compassionate, and many don't consider him particularly honest.

But the billionaire businessman is overwhelmingly viewed as decisive and competent, which is what matters most to GOP voters right now.

A new AP Poll found that 8 in 10 Republican voters call Trump very or somewhat decisive putting him at the top in the field.

But cause for concern for Trump.

Thirty-eight percent of Republican voters give him an unfavorable rating.

That ranks as the highest negative mark of those polled.