The two candidates differ starkly on how to protect France, with Le Pen calling for the country to take back control of its borders from the European Union and deport all foreigners on a terror watchlist. Macron, an advocate of open borders, has urged French citizens not to "give in to fear".
Karim Cheurfi, a 39-year-old Frenchman, shot and killed police officer Xavier Jugele and wounded two others on the world-famous Paris avenue on Thursday, in an attack claimed by the Islamic State group. Cheurfi was killed in return fire.
President Francois Hollande will Tuesday morning pay homage to Jugele at the ceremony at his Paris police precinct during which he will be awarded one of France's highest honours and be posthumously given the rank of captain.
Jugele's civil partner will also speak, and both presidential candidates have said they will be present.
The first round of the presidential election on Sunday saw outsiders Macron and Le Pen trounce France's traditional party candidates, revealing a country deeply divided as they head into the May 7 runoff.
Macron is the clear favourite to become France's youngest-ever president after topping the first round with 24 percent of the vote, ahead of National Front (FN) leader Le Pen on 21.3 percent, according to final results.
Hollande on Monday urged voters to reject Le Pen, warning of the "risk for our country" of a far-right victory and said he himself would vote for Macron, who served as his economy minister for two years.
Thanking Hollande in a tweet for his support, the former investment banker called on the French to "remain true to France's values" in the runoff.
Le Pen seized on the flurry of endorsements for Macron from the ruling Socialists and main opposition Republicans -- both of which crashed out in the first round -- as proof he was the choice of a discredited old guard.
"Nothing in either Mr Macron's policies or his behaviour suggests the slightest proof of love for France," she said. "We are going to win."
Macron and Le Pen will take part in a TV debate on May 3.
According to two opinion polls that were carried out on Sunday night, Macron would beat Le Pen by 62-64 percent to 36-38 percent.
Sunday's results were a stunning blow to France's traditional political class, with voters fleeing the ruling Socialists and conservative Republicans who have governed for the past half-century.
Republicans candidate Francois Fillon was seen as the favourite until January when his campaign was torpedoed by allegations that he gave his British-born wife and two of his children fictitious jobs as parliamentary assistants.
In the end, Fillon trailed in third with 20.01 percent, ahead of radical left candidate Jean-Luc Melenchon on 19.58 percent.
Fillon and fifth-placed Socialist candidate Benoit Hamon have both rallied behind Macron, but Melenchon has pointedly avoided backing the centrist.
'Patriots v nationalists'
Addressing thousands of flag-waving supporters in Paris on Sunday evening, Macron said he aimed to unite "patriots" against "the threat of nationalists".
Le Pen, who has been hoping to emulate Donald Trump's victory in the US, said the French faced a choice between "runaway globalisation" and a protectionist France.
Her plans to restore France's borders with its European neighbours, pull out of the eurozone and hold a referendum on leaving the EU had sown fear of another devastating blow to the bloc after Britain's vote to leave.
Le Pen gained over 1.2 million new voters compared with her last presidential bid in 2012, securing 7.7 million ballots, a result she hailed as "historic".
She follows in the footsteps of her father Jean-Marie, who made it through to the 2002 presidential run-off in what was a political earthquake for France, but went on to suffer a stinging defeat.
Sunday's first round capped a rollercoaster campaign in a demoralised France, which has been rocked by a series of terror attacks since 2015 and is struggling to shake off a deep economic malaise.
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