In his first fundraising quarter since entering the race, Cotton, R-Ark., brought in approximately $1.072 million, while Pryor accrued roughly $1.067 million during the same period from July through September.
Pryor, D-Ark., widely considered among the most vulnerable Democratic incumbents seeking reelection in 2014, did not see a significant fundraising boost after Cotton entered the race in August, and his take was down slightly from the previous quarter, when his campaign recorded $1.2 million in receipts.
But the expectations were perhaps even greater for Cotton, who has attracted attention from big-money Republican donors, including former President George W. Bush, and is seen by Republicans as one of their best bets to capture a Democratic Senate seat.
Pryor's campaign played down Cotton's narrow edge, saying that with his national backing they expected him to raise twice as much money as he did.
Cotton has been criticized by Democrats for some of his fundraising efforts, including for missing a House vote to attend a fundraising event in Texas.
Pryor, for his part, plans to tap former President Bill Clinton, a former governor of Arkansas, to help raise money and to campaign with him in Arkansas as Election Day nears.
Note: An earlier version of this story misstated the amount of money raised by Pryor due to an error by his campaign.