Regardless of where you stand on the EU referendum, let's pause and take a quick look at Zac's decision to back Brexit.
The latest poll (before Zac said he was part of the 'Out' camp) showed Khan led by 140,000 votes.
Now, there are 1.2 million Europeans living in London, 559,543 who are registered to vote in the Mayoral election.
This section of the electorate can make or break his campaign - and he has prety much guaranteed that they almost exclusively vote against him.
Most commentators think he can now say "au revoir" to his hopes of being mayor. In some ways I think this was a really foolish decision. But in others, I feel he has stuck to his principles even though they are not popular in his electorate - something quite refreshing in 21st century British politics.
Maybe he realised he doesn't want to be Mayor any more, and this is a quick way out...
The most recent mayoral poll suggested the gap between Mr Khan and Mr Goldsmith was about 140,000 votes.