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.) is pushing back against Rep. Tom CottonThomas (Tom) Bryant CottonProtecting American innovation Russian spy poisoning brings world powers closer to day of reckoning GOP senators see Tillerson ouster as the new normal MORE's (R-Ark.) recent TV attacks on immigration, using quotes from Sen. John McCain (R-Ariz.) to do so.

Pryor is up with a new ad featuring McCain's quote that "anyone who calls it amnesty is not being intellectually honest," firing back at a recent Cotton ad that says Pryor "voted for amnesty [and] citizenship for illegals."

"Mark Pryor voted the same way as John McCain and many other Republican senators," Pryor's ad fires back. "Secure the border first. Pryor voted no amnesty, 20,000 new border agents, a 700-mile fence and a long-term solution. It's tough but fair. While Congressman Cotton voted to cut funding for border protection and played politics with our security."

With the ongoing humanitarian crisis at the border, immigration has taken on renewed life as a 2014 campaign issue in a number of states.

Pryor and Cotton are locked in a tight race, according to polls.