ITV News' Political Editor Robert Peston understands the Mayor of London, Boris Johnson, will be joining the campaign to leave the European Union.
Mr Johnson is expected to formally announce his decision to align with the 'leave' camp against the Prime Minister on Sunday evening.
David Cameron has warned that Britain has "100 days to secure our future", as a poll suggests the final result hangs in the balance.
The EU referendum is a choice between "the devil and the deep blue sea", one of the UK's most senior business leaders is to say today.
Britain's car industry is an economic success story, and with uncertainty over the impact of Brexit, it wants to stay put.