France's political course is likely to remain far from certain even with a win for presumed victor Emmanuel Macron, as his inability to form a parliamentary majority threatens to undermine his authority both domestically and across Europe, political analysts have suggested.
Sunday's second round runoff will mark the start of a period of tension for the country as the successful candidate waits to see if they can garner a large enough parliamentary majority in June's legislative election to enact change, Dominique Reynié, professor of political science at the Sciences Po institute in Paris, told CNBC Tuesday.
"I'm not worried about Macron's ability to win, but the question surrounds what kind of turnout he will achieve and what his ability to gain a majority in the June election will be," explained Reynié.
Polls are currently pitching centrist Macron to gain anywhere from a 59 percent to a 64 percent lead on his far-right opponent Marine Le Pen.
However, this lead will do little to boost Macron's authority in government, Reynié suggests. The independent will have to gain significant support from other parties if he is to form a majority when France once again heads to the polls on June 11 and June 18 to elect the 577 members of its National Assembly.
"It will all depend on his margin of victory. A 55 to 45 percent win for Macron would be a disaster. Even 60 to 40 is not at all a triumph; a 20 percent margin would be very difficult.
"It would be a crisis. It is not normal and would be a problem both on the streets of France and for Europe," said Reynié.
In the first round of voting, Macron's En March!, or Onwards! party, achieved a majority in 240 constituencies versus Le Pen's 216. However, Reynié says this is simply not enough.
"The smaller Macron's majority the harder it will be for him to win the general election in June. He needs support; it is not possible to have power as President without support.
"This could cause parliament to be largely fragmented like in the first round, with discussions taking place in fractured groups. Macron will have to negotiate with MPs and will be fragile and unpopular."
Fellow presidential hopefuls Jean-Luc Melenchon obtained 67 seats, Francois Fillon 53 and Benoit Hamon zero. They would need to align themselves with Macron in order for his polices to receive approval.
While former opponent Fillon spoke out for his voters to back Macron in a bid to ward off rising support for Eurosceptic Le Pen, other candidates have been less willing to offer him their support.
In 2002, when Le Pen's father and the founder of the National Front, surprised voters by making it through to the second round, campaigners rallied to throw support behind his opponent Jacques Chirac.
"The context has changed," Marjorie Alexandre, confederal assistant at workers union Force Ouvriere, told CNBC Tuesday, the day after protestors took to the streets of France for traditional pre-election May Day protests.
"We are here to defend workers' particular rights; we are not here to defend the rights of the nation," she said, arguing that she would not encourage members to support Macron in order to stave off Le Pen.
Meanwhile, Le Pen showed a change of tact over the weekend when she teamed up with former rival right wing politician Nicolas Dupont-Aignan and softened her stance on one of her flagship policies, suggesting there would not be an imminent departure from the euro. The move comes as part of her efforts to widen her appeal, particularly among right-wing voters.
Le Pen told the Sud Ouest newspaper that "if everyone is agreed we could take a year or a year and a half to organise a co-ordinated return to national currencies," allaying fears of a sudden exit from currency union, which opponents said would massively hurt France's economy.
She also said that she would make Dupont-Aignan, who gained 4.7 percent in the first round of voting, her prime minister if elected.
"The point that she made on Friday, in her alliance with Monsieur Dupont-Aignan, is that you can push through economically protectionist policies without necessarily leaving the euro," Charles Lichfield, Europe associate at Eurasia Group, told CNBC Tuesday.
"She hasn't completely flip-flopped but she's moved it down the timeline a bit. I think it makes sense but I just think it's a bit too late to convince those right-wing voters and I think many will abstain if they can't vote for Macron."
The move could threaten to undermine Macron's chances of gaining undecided voters, and could further increase the anticipated high voter abstention levels. Already it is expected that the upcoming holiday weekend will impact voter turnout, hurting Macron most significantly.
"French people are less in favour of Europe than the euro, but now Le Pen has moved on this so it has become more difficult for voters to vote for Macron," explained Reynié.
"He's a sort of centrist but he's coming from the left of government so he's a difficult choice for right-wing voters.
The two are set to face each other Wednesday evening in their first head-to-head televised debate since the first round knockout.
The opponents attacked each other's records in May Day rallies Monday. Macron denounced Le Pen as a "danger for democracy" while Le Pen criticised Macron's establishment roots, calling him a "puppet of finance."
French voters will head to the polls on Sunday May 7.