Rep. Jason ChaffetzJason ChaffetzDem demands documents from TSA after scathing security report Chaffetz replacement sworn in as House member Democrats expand House map after election victories MORE (R-Utah) announced Monday that he wont challenge Sen. Orrin HatchOrrin Grant HatchMcConnell names Senate GOP tax conferees Ryan pledges 'entitlement reform' in 2018 Utah governor calls Bannon a 'bigot' after attacks on Romney MORE (R-Utah) in a 2012 primary battle.

After months of saber-rattling by the conservative, second-term lawmaker about a potential challenge to Hatch, Chaffetz said that he won't run, The Salt Lake Tribune reported this afternoon.

“If I were to run an interparty battle it would be a multimillion-dollar bloodbath,” Chaffetz at a press conference in Utah, according to the paper. “I don’t think that’s necessarily in my best interests. I don’t think it’s in the best interest of our party, the nation or our state.”

Chaffetz's decision follows diligent work by Hatch in recent months to shore up conservative support in order to fend off a primary challenge. 

"We wish Congressman Chaffetz the best in his congressional campaign and in his continued service as one of Utah's representatives," said Hatch campaign manager Dave Hansen in reaction. "Senator Hatch looks forward to continuing to work together as a delegation to find solutions to the critical issues facing Utah and our nation."

The veteran Utah senator had tacked to the right by partnering with his fellow Utahn Sen. Mike LeeMichael (Mike) Shumway LeeSupreme Court takes on same-sex wedding cake case House approves motion to go to tax conference — with drama Trump really will shrink government, starting with national monuments MORE (R), a Tea Party favorite, to forcefully support a balanced-budget amendment to the U.S. Constitution. Hatch had also aligned himself with conservatives on a series of votes this session, voting against the most recent debt-ceiling compromise and against the 2011 budget compromise that prevented a government shutdown. 

The two have also traded barbs through the press in what had been seen as a preview of the eventual campaign. Hatch said he thought Chaffetz could be a "halfway decent congressman" if he were to focus on his job, while Chaffetz questioned Hatch's voting record during a long career in the Senate.

At the same time, Hatch's campaign has courted high-profile conservative pundits to endorse his renomination. Radio hosts Sean Hannity and Mark Levin lent their support to Hatch, which his campaign proudly trumpeted.

The campaign is a study in contrasts from Sen. Dick Lugar (R-Ind.), who's also facing the threat of a conservative primary challenger but has embraced defended some of the centrist votes he's made.

Hatch appears to have learned from the experience of his former Utah colleague, Sen. Bob Bennett (R), who lost renomination to Lee in the 2010 primary process. Bennett aggressively stood by his record as an establishment-minded Republican at a party convention last year dominated by Tea Party activists. 

Chaffetz had said earlier that he planned to make a decision on the race sometime later this year; the late August announcement is much sooner than expected.

The congressman's decision not to run for Senate doesn't forestall a future career in the upper chamber — Chaffetz is still relatively young. His decision also wouldn't guarantee that Hatch won't still face a primary challenger, though no conservative candidate would have the kind of experience and infrastructure that Chaffetz would have brought to the contest.

Updated 9:37 p.m.