"These disgruntled Hillary [sic] suppporters are related by blood to me but like leftists everywhere, they put political ideology before family", he wrote Saturday afternoon.
In their ads for David Brill, the Democratic challenger in Gosar's rural north-western Arizona district in the November midterms, the various other Gosars do not mention Tommy Robinson.
In the ad, the siblings criticized their brother's views on issues like health care and immigration, and argued that Paul Gosar doesn't have Arizonans' interests at heart.
He continued in another tweet, explaining "You can't pick your family".
In another tweet, he complained: "We all have insane aunts and relatives etc and my family is no different", before adding: "To the six angry Democrat Gosars-see you at Mom and Dad's house!"
Then comes the big, brutal reveal: all six of the people who appear in the ad are actually Gosar's siblings.
A woman called Grace, identified as a rural physician, says: "Paul Gosar, the congressman, isn't doing anything to help rural America".
Gosar was quick to point out an interview his mother, Bernadette Gosar, did with the New York Times in which she decried the ad and said she was both "shocked" and "crushed".
"I share the same philosophy and policies that Paul does", the newspaper quoted her as saying.
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Six of GOP Rep. Paul Gosar's nine siblings are campaigning against him.
'None of this is pleasant for any of us, ' says brother David Gosar, a lawyer, noting that 'We gotta stand up for our good name.
Paul Gosar, Tomi Luhren, Mike Cernovich, and Brandon Tatum appear as Kelli Ward campaigns at the Gunsite academy in her bid to become the Republican nominee for an open Senate seat in Paulden, Arizona, U.S. August 24, 2018.
Gosar was pretty much forced to respond in some way, which he did on Saturday - by citing Josef Stalin, naturally. "Those aren't our family values or the values of the small Wyoming town we grew up in".
The other videos were titled, "A Rural Doctor's Personal Healthcare Story" and "Paul Gosar Is Not Working For You". Gosar also flew to London to speak at an anti-Muslim rally, with his travel funded by the anti-Muslim Middle East Forum group.
"I couldn't be quiet any longer", says Grace Gosar.
"It's intervention time", he said, "when you go to vote, you go to vote...to vote Paul out".
It's just the latest ad to feature a politician's family member this year.
In addition to the ads, Joan, who lives in Idaho Falls, Idaho, donated $1,000 to Brill's campaign, filings show.