Bookmakers will be counting their losses after David Cameron defied expectations by racking up more than 100,000 followers on Twitter in a matter of days.
Some firms offered 25/1 odds of the Prime Minister reaching the target by the end of the Conservative Party conference being held in Birmingham and will now have to pay out thousands to punters.
Ladbrokes has now slashed its odds on him notching up one million followers this year to 2/1 from 66/1.
Mr Cameron once said that he would steer clear of the site, which allows users to send out messages in 140 characters or fewer, famously saying that he was worried that "too many tweets make a t***".
But he became the 370th MP to start an account at the weekend and has posted a number of messages about his activities during the conference.
He said: "In this modern world you have got to use every means to try and communicate your message and explain to people why you are doing it. You've got to get with the programme, I suppose."