Sen. Mark PryorMark Lunsford PryorMedicaid rollback looms for GOP senators in 2020 Cotton pitches anti-Democrat message to SC delegation Ex-Sen. Kay Hagan joins lobby firm MORE (D-Ark.) raised more than $1.1 million in the last three months of 2013, bringing his total haul for the year to $5.3 million.

Pryor, who's viewed as the most endangered senator facing reelection next year, has $4.2 million in the bank for his tough race.

"Heading into the election year, Mark will have every resource to remind voters about his record as a reliable and responsible voice for Arkansas families, while drawing clear contrasts with Congressman Cotton's reckless agenda that puts his own interests ahead of Arkansans," said Pryor campaign manager Jeff Weaver.

Rep. Tom Cotton (R-Ark.), Pryor's opponent, has yet to release his fourth quarter fundraising totals. He had $1.8 million in the bank as of the end of September after raising $1 million in the previous quarter.

Pryor's cash on hand actually dipped from the $4.4 million he had three months ago, a sign of how expensive the race is already becoming. Both Pryor and Cotton were on the air with campaign ads in December, and outside groups on both sides have been spending heavily on the race.

This post was updated at 3:20 p.m.