It's worth reiterating here that TV and radio stations are bound by FCC rule to offer political advertisers, including candidates, the lowest rate for a given daypart that any advertiser pays that station during the defined campaign season.
That might make it sound like political advertisers get dramatic bargains when they buy time, but in reality, it's more of a boondoggle for the stations not because they offer candidates super-deep discounts on rates, but because they get to charge all the other advertisers elevated rates under the guise of not being able to offer their customary rates because it's running during "politicals". It's why we see almost 100% of prime-time local spots being political during the season: few other advertisers can afford to run at those elevated rates. So they either rush into other, cheaper dayparts; shake up their media or station mix for the time being; or just go on hiatus until it's all over. Steady advertisers like QSRs and dealer groups, who run promotional pillars basically 52 weeks a year and can't afford to go dark for even a week, simply budget double-digit CPP increases in the short-term and just deal with it.