“Josh Hawley has no shame and put his own personal ambitions ahead of America. JOSH PAC will work to ensure that Hawley never wins another election,” the source said.

The PAC, which raised $15,000 in just a few hours Friday, will launch with three former McCaskill campaign staffers on board: Travis Mockler, Thomas Hatfield and Zoe Gallagher.

Hawley was the first senator to announce he would join House Republican challenges to the election; a dozen other senators announced plans to object to Electoral College certification after Hawley did. After rioters ransacked the Capitol last week, Hawley voted not to certify Arizona’s results and also objected to Pennsylvania’s certification. He has condemned that day’s violence.

But media outlets, former Sen. John Danforth (R-Mo.) and donors have all been critical of Hawley’s role in challenging the election on the day a pro-Trump mob stormed the Capitol. The subsequent invasion of Congress led to five deaths and desecration of the building.

Hawley has largely been unapologetic, comparing his efforts to past Democratic challenges to elections. One major difference: The Democratic candidates had conceded those elections, while President Donald Trump kept fighting to overturn the election into last week.

Kelli Ford, a spokesperson for Hawley, said: "We expect Claire McCaskill and her team will be as effective with this campaign as they were with the last. They wasted more than $60 million in 2018 — and lost — after Missourians rejected Claire McCaskill’s failed liberal policies."

McCaskill was unaware of the formation of JOSH PAC, the source familiar with the effort said.

Hawley also defended his actions in an op-ed this week.

“Much of the media and many members of the Washington establishment want to deceive Americans into thinking those who raised concerns incited violence, simply by voicing the concern,” Hawley wrote in the Southeast Missourian on Wednesday. “But democratic debate is not mob violence. It is in fact how we avoid that violence.”