The feud between Third Way and Sen. Elizabeth Warren (D-Mass.) has surfaced in a way the corporate-backed think tank probably didn't intend.

After Warren sent a fundraising email on behalf of Sen. Mark Pryor (D-Ark.), the campaign of Rep. Tom Cotton (R-Ark.), his opponent in the Senate race, noted that Third Way co-founder Matt Bennett had called Warren's economic message "catastrophically antibusiness" at the 2012 Democratic National Convention.

The "catastrophically antibusiness" line was also used by the Chamber of Commerce and Sen. Scott Brown's (R-Mass.) campaign before Warren defeated him in 2012.

"Senator Mark Pryor is turning to help from his Washington ally Elizabeth Warren, a notoriously liberal Senator whose views are radically out-of-touch with Arkansas," Cotton's campaign also wrote on Friday, characterizing Warren as "radical" and a supporter of "European-Style, Single-Payer" health care. Cotton's campaign identified Third Way as a "leading Democratic think tank."

Cotton's attempt to tie Pryor to Warren echoes how Pryor is working to paint Cotton as extremely conservative.

Third Way didn't respond to a request for comment about Cotton's attacks on Pryor and Warren.

The think tank's co-founders wrote in Politico in March that only a "big tent" approach could help Democrats keep their Senate majority. In their piece, they referred to Pryor's "tough reelection battle":

If we are to make progress in a divided Washington -- and if we are to protect the Democratic Senate majority -- we simply must embrace a big tent for the Democratic Party. Even in purple states, there are not enough self-identified liberals to elect Democrats without their winning significant pluralities or majorities of moderates. The idea that more liberal candidates could win in places like Arkansas, Indiana or Alaska is pure fantasy. And to write off those states would consign Democrats to long-term congressional minority status.

After leaders of Third Way penned a December Wall Street Journal editorial criticizing Warren's stance on Social Security, Warren challenged Wall Street banks to open up about donations they make to think tanks, in a volley back at the group.