In the 2012 Missouri Senate race, incumbent Democrat Claire McCaskill ran ads during the GOP primary campaign saying that Todd Akin was "too conservative." The idea of the "attack ad" was to drive GOP voters to Akin, her weakest potential foe. It worked.
Others have since copied the tactic.
James Arkin at Politico:
A mysterious new super PAC with links to Democrats released a TV ad on Wednesday meddling in next month's Kansas Republican Senate primary.
The super PAC, Sunflower State, formed on Monday and two days later launched its first TV ad, focused on Kris Kobach and Rep. Roger Marshall, two of the Republicans running in the Aug. 4 primary. National Republicans have expressed concern that Kobach — the former secretary of state who lost the 2018 governor's race to Democrat Laura Kelly — would put the seat in jeopardy if he becomes the nominee, while Marshall has attempted to consolidate support from the establishment in the primary.
The ad is engineered to drive conservative voters toward Kobach. A narrator in the ad calls Kobach "too conservative" because he "won't compromise" on building President Donald Trump's border wall or on taking a harsher stance on relations with China. By contrast, the ad labels Marshall as a "phony politician" who is "soft on Trump."
Sunflower State has apparent ties to Democrats. The media buyer used to place the ad, Old Town Media, was also used to place more than $11 million in ads from Unite the Country, the pro-Joe Biden super PAC that spent heavily in the Democratic presidential primary. Sunflower State also holds its account at Amalgamated Bank, which is used by Senate Majority PAC, a top Democratic outside group, among other prominent Democratic groups, including Biden's campaign, according to the filing with the Federal Election Commission.
KANSAS: New ad from Democratic super-PAC intervening in Republican Senate primary refers to Kris Kobach as "the pro-Trump conservative leader" and Roger Marshall as "the swamp creature." Mostly attacks Marshall. 7 days to primary. #kssen pic.twitter.com/VwDy8LQQB3— Greg Giroux (@greggiroux) July 28, 2020