Pryor is viewed by strategists in both parties as the most vulnerable Democratic senator up for reelection this cycle, and his seat is a must-win for Republicans if they hope to take back Senate control. Cotton is a favorite of both the Tea Party and establishment Republicans.
"Arkansans need leaders who are standing up for them in Washington, not self-serving politicians like Tom Cotton who care more about their personal political ambition instead than fighting for Arkansas," said Barasky.
Cotton's spokeswoman said on Wednesday that the lawmaker "strongly supports all efforts to defund, delay and ultimately repeal Obamacare, regardless the legislative approach."
Cotton told radio host Hugh Hewitt earlier this summer that upcoming fights over the debt ceiling and a spending bill could be critical in blocking the president's healthcare reform bill.
"I think that when we return from our August recess in September with our continuing resolution and then in October-November with the debt ceiling, those are important opportunities to try to strike another blow against ObamaCare before that law takes effect, before the insurance marketplaces begin to open for enrollment on October 1 and before they open for business on January 1," Cotton said.
"And whether that takes the form of trying to defund it or trying to effectively defund it by delaying for a year or two years the core provisions ... because those are two must-pass pieces of legislation it gives us an opportunity to defund ObamaCare before it takes effect."
A number of Senate Republicans have slammed the idea of using the debates to try to defund the healthcare law, which has been pushed by Sen. Mike Lee (R-Utah).