A poll released Monday by Hickman Analytics Inc. shows Cotton with 51 percent support compared to 42 percent for Pryor among voters most likely to turn out in November. Though Pryor has used the firm for polling in the past, he is not currently a client, according to his campaign.

Among a broader swath of voters, including those less likely to turnout, Pryor closes the gap with Cotton, with the candidates each tallying 46 percent.