Only one station contacted by Lee Newspapers said responded to an inquiry and said they had consulted their lawyers and would not be taking down the ad.
It’s not clear yet what are the next steps Pioneer will take.
In the first letter to TV stations, Archibald said he was “appalled to see the advertisement.”
“To imply any sort of nepotism at play is not only offensive but downright false,” Archibald wrote.
NRSC said it stands by the ad’s claims, citing Bill Bullock’s role as chairman of the board.
“Public state filings show Gov. Steve Bullock’s brother to be the chairman of the board of a corporation that has received more than $14 million in taxpayer funds during this Democrat administration,” said NRSC spokesman Nathan Brand. “Montanans deserve answers from Steve Bullock about how his brother’s company secured such lucrative state contracts, and why this conflict of interest was not disclosed to Montana taxpayers.”