A shooting on Thursday night on the Champs-Elysees shopping boulevard in central Paris, in which one policeman was killed and two others were wounded, could bring campaigning to a sombre and abrupt end, however.
A man emerged from the vehicle and opened fire on the van with an "automatic weapon", killing one officer instantly, Brandet said.
The Paris prosecutor's office leading the investigation of the Champs-Elysees gun attack says investigators found a pump-action shotgun and knives in the gunman's auto. Cheurfi's identity was confirmed from his fingerprints.
Francis Kalifat, the president of the CRIF umbrella group of French Jewish communities, added his voice to the many condemnations of the attack.
The risk for the main presidential candidates is misjudging the public mood by making an ill-perceived gesture or comment.
The exchange was notable for several reasons - for one, Macron is a candidate, not a president-elect, and he is an upstart: Only 39, he's a former banker turned politician and has never held elected office.
The far-right candidate, Marine le Pen, demanded the closure of all Islamist mosques.
Le Pen, who leads the National Front, has made immigration and security a core part of her campaign.
While analysts have deemed it unlikely that the National Front leader will be able to win the penultimate vote whoever she faces, a great many pundits are pointing to incorrect predictions about Brexit and Donald Trump after failing to feel the rising pulse of right-wing populism.
Even before French President Francois Hollande said he was convinced the Paris attack was "terrorist related" it had impacted on the effort to find his replacement. "Make sure you that, as you said, you work hard all the way through".
Paris police say 2 officers killed in shooting along Champs-Elysees
The attacker was being investigated over his possible intention to kill police officers, sources close to the investigation said. French far-right presidential candidate Marine Le Pen tweeted, "My emotions and solidarity for the police, once again targeted".
France anti-terror prosecutors have opened investigation into the attack.
"The fight for the French people's freedom and security will be mine. This must be the priority", he said.
Failure by both to qualify for round two would signal a receding of the populist wave that crashed over the European Union with Britain's vote a year ago to leave. Delivery trucks did their early morning rounds.
Asked if the assault would impact voting, the centrist Macron said: "No one knows". "Will have a big effect on presidential election!"
Conservative contender Francois Fillon, who has campaigned against "Islamic totalitarianism", said on France 2 television that he was canceling his planned campaign stops Friday.
Recent polling continues to suggest that Marine Le Pen and Emmanuel Macron will move into the next round of voting.
"Sadness and anger following the attack at Champs-Elysees", Kalifat wrote on Twitter. She said her plans to vote Fillon remained unchanged. This is also the first time in modern France when the incumbent president hasn't run for a second term.
The attack appeared to fit in a spreading pattern of French extremists targeting security forces and symbols of the state, to discredit, take vengeance and destabilize.
Authorities are trying to determine whether "one or more people" might have helped the attacker, Brandet said. The two top vote-getters on Sunday will advance to the May 7 presidential runoff.