Washington (CNN) Congressman-elect Greg Gianforte's body slam of a reporter last week might have just helped Democrats hold onto a Senate seat in Montana in 2018's midterm elections.

Republicans had been eyeing the state's attorney general, Tim Fox, to take on Democratic Sen. Jon Tester. But Fox has now opted against running, two GOP sources familiar with his decision said Friday.

The reason: Gianforte was initially expected to run for governor in 2020 -- but now, Republicans expect the fallout from his body slam of Guardian reporter Ben Jacobs on the eve of the special election in which Montana elected him to the House to linger, damaging Gianforte long-term.

That, one source said, could clear the 2020 governor's race for Fox. The seat will be open because Democratic Gov. Steve Bullock is term-limited -- likely making it more appealing than an expensive race against a two-term Democratic incumbent in Tester.

Fox is the third recruiting target that Senate Republicans have lost. Initially they were looking to then-Rep. Ryan Zinke to challenge Tester -- but President Donald Trump tapped Zinke for interior secretary. Then, they considered Gianforte, but he opted to run for the House vacancy that Zinke's appointment created, instead.

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