I had thought that Dems running against the Koch bros might alienate moderate voters but it looks like fear is a powerful motivator to separate liberals from their money
Bashing the Kochs Can Triple a Democrat’s Fundraising Haul

I’ve seen some numbers from fundraising emails from one campaign that were sent from roughly mid-January to mid-March, pretty bad news cycles for the party. Nineteen emails didn’t mention the Kochs. They raised, in total, $48,146.30, for an average of $2,534.02 per message.

But five emails mentioned, in at least some way, the Koch brothers. Those asks raised $32,668.72, an average of $6,533.74 per email. The Democratic base, which has been hearing about and fearing the Kochs for nearly four years, responds to this stuff.