Nigel Farage is kicking off Ukip's campaign for Britain to vote for withdrawal from the European Union in the referendum planned by the end of 2017.
The eurosceptic party's leader announced earlier this week that he wants Ukip to provide the "ground forces" spreading the Brexit message across the country, separately from the two existing groupings which are vying for designation as official leaders of the Leave campaign.
At an event to launch the Ukip campaign in London, he is expected to give details of the drive planned by the party, including a string of public meetings around the country.
With predictions that the poll may be held as early as next spring, Mr Farage has said there is no time to waste in engaging in the referendum battle.
The launch comes after two significant climbdowns on the referendum by Prime Minister David Cameron, who is visiting Portugal and Spain for discussions on the renegotiation of Britain's EU membership which he hopes will allow him to recommend staying in.
The PM accepted a watchdog's recommendation that voters should not be presented with a Yes/No question - which eurosceptics feared would put them at a disadvantage - but should instead be asked to opt to "remain" in or "leave" the EU.
And he offered changes to restore the "purdah" rule - which bars the use of public money to promote one side in the final four weeks before a poll.
Mr Farage confirmed earlier this week that he will not seek designation for himself or his party as official leaders of the No campaign but said he was ready to "work with anybody" in the battle for withdrawal - including the No campaign set up at Westminster and the Know group launched by business figures including Ukip donor Arron Banks.
The Ukip leader claimed that people who have voted for his party over the past few years could between them deliver 60% of the vote needed to secure referendum victory.