The date for the Corby by-election has been announced as November 15th.
The by-election was forced by the decision of Louise Mensch, who secured a 1,951 majority in 2010 to quit the Commons and move to the US with her family.
Outside the conference hall in Birmingham today, a key group of voters was listening to David Cameron's every word.
In November they will go to the polls in Corby in a by-election sparked by the resignation of MP Louise Mensch.
Click here to find out what they thought of the speech.