It started with former Barack Obama speechwriter Jon Favreau sharing polling results of General Election voters in Wisconsin. The polling included how a certain line of attack used by Democrats resonates with voters:

The most persuasive message we tested against Trump was this:

“Trump proposed nearly $1 trillion in cuts to Medicare to pay for his tax cut for millionaires and billionaires”

Made voters say they were less likely to support Trump by a margin of 38 points

— Jon Favreau (@jonfavs) August 15, 2019