The starting gun has been fired in the battle to win hearts and minds ahead of the EU referendum on 23 June, as the official campaign begins.
Earlier this week Britain Stronger in Europe and Vote Leave were chosen as the designated campaigning groups ahead of the vote by the Electoral Commission, with both now entitled to spend up to £7m.
"Today marks one of the most important dates in the referendum timetable for campaigners," said Bob Posner, director of party and election finance and legal counsel at the Electoral Commission said.
It's expected that both campaigns will now be focusing on core messages to win over supporters.
As you'd expect Mayor of London Boris Johnson will be helping kick off the campaign by speaking at one of many Vote Leave events across the UK, where he will say that leaving the EU is necessary to save the NHS.
And Nigel Farage, who co-led Vote Leave's rival campaign Grassroots Out, has now called for an end to infighting on the Leave side.
On the Remain side of the debate, former chancellor Alistair Darling will today warn that there is "nothing patriotic" about backing a Brexit and "turning a blind eye to credible warnings of economic disaster".
Earlier this week Prime Minister David Cameron got together with former Labour and Liberal Democrat leaders Lord Neil Kinnock and Lord Paddy Ashdown to call voters from the Britain Stronger in Europe headquarters.
Jeremy Corbyn has also appeared to warn of the dire consequences to workers rights that would ensue a Brexit vote.
Drawing attention from across the world, Obama is soon to wade into the debate. While he's expected to acknowledge that the decision is for the UK alone, the President will advise against Brexit as a "friend".
Read more: Why are EU citizens coming to the UK?
However, the pro-Remain government has come under fire for spending £9m of taxpayers money on a pro-EU leaflet to be sent to households ahead of the referendum.
In fact, it has aggravated the public so much that the issue will be debated in the House of Commons in May after a petition garnered over 200,000 signatures.
Current polling puts Remain and Leave neck-and-neck, indicating that the outcome will be determined by which side can better get its supporters to turn up and vote on the day.
It's in that spirit that Cameron has been appealing to younger voters, with Britain Stronger in Europe even launching a "Talk to Gran" campaign.
But Leave has been cut by bookmaker Betway from 7/4 to 13/8 on the first day of campaigning. Remain is still a strong favourite at 4/9.