polls sway one way or another after events driving them, they don't just change for no reason. Repubs are flooding the market with biased polls to change the narrative; 25 of the last batch of polls were Republican-aligned "run by or paid for by the Republican establishment". They're doing the same with the betting markets; some whale was found to flood 30mil worth of bets through 4 accounts to sway the odds. 

I've never seen a party go that far to alter the narrative instead of campaigning.