We found 44 still-active accounts tweeting the text "Donald Trump teases 'big announcement' in Iowa" accompanied by a link of some sort. Hilariously, a couple of them tweeted it in September 2017, over a year late to the party. 
Of those 44 accounts, 20 were flagged as bots based on 90+% of tweets being posted via automation services, 24/7 activity, or both. 5 of those were the official accounts of radio/TV stations, but the other 15 are interesting. . .
The majority of these bots are extremely prolific. All but two have over 500K tweets, with one of them (@amandsst) having tweeted 2051057 times in a little over four years. #Spamtastic
