"Today, there's not a Jewish person in Pittsburgh who can get through a Shabbat dinner without thinking about what happened on October 27, 2018," Frankel said. "Anyone in my community can tell you that they now carry a seed of fear with them anywhere they go."

Just two hours before the shooting, the gunman wrote a Gab post promoting the white supremacist "great replacement" conspiracy theory, which baselessly claims that elites in Western countries are importing people of color to the United States in order to dilute the political power of white majorities.

"I can't sit by and watch my people get slaughtered," the gunman wrote. "Screw your optics. I'm going in."

Mass shooters across the globe have invoked the conspiracy theory to justify their actions, and some Republican politicians have used elements of it in their campaigns, including U.S. Rep. Elise Stefanik (R-NY), the third-ranking Republican in the House of Representatives.

Andrew Torba, the owner and founder of the social network, openly entertains antisemitic conspiracy theories ancient and modern, referring to Jewish people as "Christ killers," encouraging users to share "differing opinions" on the Holocaust on his website, and declaring that Jewish conservatives are "not welcome in the movement" unless they embrace Christianity.

Pennsylvania state Rep. Malcolm Kenyatta, a Democratic rising star and the first openly LGBTQ Black lawmaker elected to the state legislature, called Mastriano "without a doubt the most extreme, most dangerous, most unhinged nominee from a major party for governor in Pennsylvania history."

"Doug Mastriano cannot become governor of Pennsylvania. His antisemitism is disqualifying, his racism is disqualifying, his homophobia is disqualifying," Kenyatta said.

While it's unclear exactly what Mastriano's campaign got in exchange for its $5,000 contribution to Gab, the Huffington Post reported that all new accounts on Gab automatically follow his account on the website.

Other far-right Republicans have accounts on the website. That includes Kari Lake, Trump's pick for Arizona governor, and Arizona state Sen. Wendy Rogers, who was censured by her party after speaking at a political conference hosted by a white nationalist. Mastriano endorsed Rogers' reelection bid this week.

Pennsylvania Attorney General Josh Shapiro, the Democratic nominee for governor, previously subpoenaed the company that hosts Gab's data, Epik.com, for documents detailing the relationship between the two in the wake of the Tree of Life massacre. Shapiro, who would be the second Jewish governor of Pennsylvania, later dropped the civil probe.

While the Republican candidate has not directly addressed the controversy, his Twitter account did retweet a post calling his payment to Gab "100% legit and creative campaigning."

"It is beyond comprehension that Doug Mastriano has avoided the press, has avoided taking responsibility and accountability for this association with Gab and Torba," Frankel said after Wednesday's press conference. "I don't know if you've taken a look at this site, it's just one antisemitic slur after another."

Numerous Jewish groups have called on Mastriano to reject Gab and cease promoting his candidacy on the website.

"Mastriano's politics literally teeter on the edge of the kind of extremism that has never been this close to a statehouse, let alone to any credible elected office," Anti-Defamation League CEO Jonathan Greenblatt said earlier this week.

"We strongly urge Doug Mastriano to end his association with Gab, a social network rightly seen by Jewish Americans as a cesspool of bigotry and antisemitism," Matt Brooks, the executive director of the Republican Jewish Coalition, told the Philadelphia Inquirer.

Mastriano was seen as too radical to win a general election by many in the Pennsylvania Republican party, elements of which launched a shambolic, last-minute attempt to deny him the nomination. However, some parts of the state establishment that worked to defeat Mastriano in the primary now appear to support him. The Commonwealth Partners Chamber of Entrepreneurs, a free-market advocacy group that supported one of Mastriano's primary opponents, said earlier this week that they would spend $8.5 million supporting his campaign.

"I'm not a fan of the Commonwealth Partners' politics, but this is really beyond that," Kenyatta said. "This guy is uniquely radical, uniquely extreme."

On Wednesday evening, Republican National Committee member Andy Reilly, a prominent state Republican who was previously involved in the anti-Mastriano effort during the primary, cohosted a barbecue fundraiser for the candidate in the Philadelphia suburbs.

"Doug is for limited government and protecting Pennsylvanians' freedoms," Reilly told the Inquirer. "I do abide, for the record, by the old Ronald Reagan adage: that someone you agree with 80 percent of the time is your friend."

In a Facebook video on Wednesday, Mastriano obliquely addressed the Gab controversy for the first time — while still refusing to distance himself from the white supremacist website.

"I know the attacks have increased, I'm certain hopeful and confident that nobody on this live feed believes the complete trash and lies with the latest attack from the media. What's the point of addressing that? It's kind of like 'Why are you beating your wife?' questions," Mastriano said in the video. "I've made a decision for most of these baseless claims and attacks against me not to respond."