The group backs up that widely held belief by arguing that Pryor's strong fundraising, family name recognition and help from the Clinton family won't help him much.

"Meet Blanche Lincoln 2.0," NRSC Political Director Ward Baker writes in the memo. "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 has the name, has the money, has the Clinton machine, and is running for reelection in Arkansas, a state that proved those talking points won’t get you very far if you are fundamentally misaligned with the electorate."

Pryor, a two-term senator and son of a former senator, has had strong fundraising to date and is well-known in the state. Polls show him in a tight race with freshman Rep. Tom CottonThomas (Tom) Bryant CottonGOP senator says Iran needs to 'stop acting like an outlaw' Sen. Tom Cotton: 'Memorial Day is our most sacred holiday' The Hill's Morning Report — After contentious week, Trump heads for Japan MORE (R-Ark.), and most pundits believe he's the senator facing the toughest race this cycle. But he's in a better position than Lincoln was — polling more than a year out before her reelection found her trailing by 20 points.

Pryor's campaign fired back.

"In case you missed Tom Cotton's lackluster initial fundraising quarter and his weeks of bad press in Arkansas for cheerleading a default and shutdown, this ridiculous memo says everything about how nervous Cotton's allies are about his candidacy," Pryor spokesman Erik Dorey said.

This post was updated at 11:30 a.m.