The unifying theme I gathered from the advertising around here in SW Pennsylvania was "They are going to take away our pre-existing condition covereage." Particularly, they played that theme over and over and over again in our neighboring district (which went for Trump in 2016), they pounded this theme repeatedly. Pretty Boy Conor Lamb made that and his military service in the USMC (without pointing out that it was 14 months as a desk jockey in Okinawa) and the claim that he wouldn't vote for Nancy Pelosi as speaker the centerpiece of his campaign, soundly defeating the frumpy but competent Keith Rothfus.
Just on the basis of commercial count, I'm guessing that Rothfus was outspent by at least four to one.
“They are going to take away our pre-existing condition covereage.”
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It was a national campaign. Heard the exact same words here in WI.