Rep. Greg Gianforte Gregory Richard GianfortePence seeks to boost Daines in critical Montana Senate race On The Trail: How Nancy Pelosi could improbably become president Supreme Court denies push to add Green Party candidates to Montana ballot MORE (R-Mont.) officially filed to run for governor of Montana on Thursday and is slated to make his official announcement on June 14 at the state's party convention, a source with knowledge of his decision told The Hill.

"He filed paperwork this evening to run for gov. Will make a formal announcement next Friday at state GOP," the source said.

Gianforte previously indicated to multiple GOP lawmakers he anticipated declaring his candidacy as soon as Friday, sources familiar with the conversations said.

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The Montana Republican, who was elected to the at-large seat during a special election to replace then-Interior Secretary Ryan Zinke Ryan Keith ZinkeTrump extends Florida offshore drilling pause, expands it to Georgia, South Carolina Conspicuous by their absence from the Republican Convention Trump flails as audience dwindles and ratings plummet MORE in 2017, recently told House colleagues of his plans to seek higher office after much speculation about whether he would enter the race, a GOP member confirmed.

“I asked him about the rumors, and he confirmed and indicated the announcement would be Friday,” one Republican lawmaker said.

The discussions come ahead of the Montana Republican Party convention, which is scheduled to be held June 13 to 15.

Gianforte met with members of House GOP leadership earlier this year to make them aware of his potential bid but had not solidified his decision at that time, two senior leadership sources said.

He has expressed strong interest in running for the position.

"I'm still considering it. I'm collecting input from across the state, visiting folks," Gianforte told The Hill on Tuesday, adding that he will “make a decision soon” and saying “stay tuned” with a smile.

Gianforte, one of the wealthiest members of Congress, would be facing at least four other Republicans in the primary: Montana Attorney General Tim Fox, Montana Secretary of State Corey Stapleton, state Sen. Al Olszewski and former state Sen. Gary Perry.

The Montana lawmaker previously ran for governor in 2016, losing by 4 points in his race against Democratic Gov. Steve Bullock Steve BullockMcConnell locks down key GOP votes in Supreme Court fight Senate Democrats demand White House fire controversial head of public lands agency Pence seeks to boost Daines in critical Montana Senate race MORE.

Bullock is ineligible to seek reelection in 2020 after serving two terms. Republicans are eyeing the open race as a potential pickup.

Scott Wong contributed. Updated June 6, 8:10 p.m.