Champs-Elysées attack: What impact on Sunday's French election? (part 1)

It was clear from the outset that this campaign would upend French politics. Then, with a little more than 24 hours of campaigning left, a 39-year-old convict targeted police on Paris' Champs-Elysées, killing an officer, injuring three, dying in a hail of bullets and stealing everyone's attention. How will this impact the election? With the top four candidates still neck-and-and neck, our panel of international journalists try to make sense of an election unlike any France has seen before.