Republican Senate hopeful Danny Tarkanian, who is challenging Sen. Dean Heller Dean Arthur HellerOn The Trail: Democrats plan to hammer Trump on Social Security, Medicare Lobbying World Democrats spend big to put Senate in play MORE (R-Nev.) for the GOP nomination in Nevada, ripped Sen. Mitch McConnell Addison (Mitch) Mitchell McConnellGraham: GOP will confirm Trump's Supreme Court nominee before the election Trump puts Supreme Court fight at center of Ohio rally The Memo: Dems face balancing act on SCOTUS fight MORE (R-Ky.) on Thursday for “smearing” conservatives amid a bitter back-and-forth between the Senate majority leader and Breitbart News executive Stephen Bannon.



Tarkanian's comments came in response to an attack leveled by the Senate Leadership Fund, an influential outside group with close ties to McConnell, which accused Bannon a day earlier of anti-Semitism.



The volley is part of an escalating feud between Bannon-backed insurgent candidates and the GOP incumbents who McConnell is seeking to protect.



Tarkanian said in a statement that McConnell’s allies are “running scared” after Sen. Jeff Flake Jeffrey (Jeff) Lane FlakeJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Republican former Michigan governor says he's voting for Biden Maybe they just don't like cowboys: The president is successful, some just don't like his style MORE (R-Ariz.) announced he would retire from the Senate after one term. Flake faced a tough path to reelection and faced a challenge from another Bannon-backed candidate in Arizona.



He said McConnell and his allies are fearful because Bannon is “helping put real conservatives — not obstructionists — in office.”



“McConnell’s smear tactic is borrowed right out of Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE’s playbook and they clearly fail to realize that Americans are sick of it,” Tarkanian said.

“I call on McConnell to get back to work and I denounce the smearing of conservatives,” he continued. “We don’t tolerate it on our school playgrounds and we shouldn’t tolerate it from our elected officials. I call on 'DC' Dean Heller to join me in publicly denouncing McConnell's smear campaign.”

Tarkanian had been pressuring Heller to sign a petition saying he would not support McConnell as majority leader.



That effort provoked a response from the Senate Leadership Fund, which was started by allies of McConnell and aims to reelect incumbent Republican senator.





Here’s another pledge for @DannyTarkanian to sign backing Bannon over ex-wife charges. #NVSen pic.twitter.com/qIHE8SrAJL — Senate Ldshp Fund (@Senate_Fund) October 25, 2017



Bannon’s allies say they’re used to being called racists by Democrats but are furious to see it coming from Republicans.



The Senate Leadership Fund's allegations stem from a 2007 court filing between Bannon and his then-wife, Mary Louise Piccard, who claimed in documents that he made anti-Semitic comments while looking at schools for his daughters.



Bannon denied the report at the time and his adviser this week called the allegations “desperate and false personal attacks” that are “further proof that McConnell Inc. is imploding in front of our very eyes."



The war between Bannon and McConnell has escalated in recent days.



Bannon has vowed to field a primary challenger for every Republican running for Senate except for Sen. Ted Cruz Rafael (Ted) Edward CruzThe Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy Murkowski: Supreme Court nominee should not be taken up before election Battle lines drawn on precedent in Supreme Court fight MORE (R-Texas), while McConnell is trying to protect the Republicans who make up his slim majority in the upper chamber.