Pryor is facing a tough re-election battle; his Senate seat is a top target of national Republicans.
Once a stronghold for Democrats, Arkansas is trending decidedly to the GOP. As recently as 2010, the party held both Senate seats, three of four House seats and controlled both houses of the state legislature.
Two election cycles later, Republicans now control the state legislature and Pryor is the last remaining Democrat in the delegation.
The partyís presidential vote in the state has also been on a decline. It has steadily dropped from Al Goreís 46 percent in 2000 to Obamaís 37 percent in 2012. If voters relate supporting Pryor to a vote in favor of Obama, heíll likely lose.
2. Both senators took controversial votes.
Republicans hope to make Pryorís support for the Affordable Care Act an issue again in 2014, when key provisions of the law will be implemented. It hurt Lincoln in 2010 and may be a negative again for Pryor.
His vote against expanded background checks on gun purchases wasnít necessarily unpopular with Democrats in Arkansas, but it invited the ire of some national Democratic donors and New York Mayor Michael Bloomberg. The mayorís pro-gun-control super PAC started expending resources in the state on Friday, spending $350,000 on airtime there to target Pryor.
3. Outside groups will target the race.
Most of the outside spending against Lincoln came in the primary. But Pryor, who has already been hit on the airwaves and in mailboxes, is likely to be a top target through the general election.
Club for Growth and Senate Conservatives Fund have already combined to spend more than $260,000 in independent expenditures on direct mail, radio and television ads that attack Pryor for supporting Obamaís agenda. They also released a poll in March showing Pryor trailing Cotton by 8 points.