Voters in Geneva put the scandal-hit Republican candidate Fillon in the lead with 34 percent of the nearly 20,000 votes cast, followed by En Marche! centrist Macron in second with 32 percent, reported 20 Minutes.
In the rest of French-speaking Switzerland Macron narrowly beat Fillion, with the two candidates taking 33 percent and 31 percent of the vote respectively.
In both areas far-right candidate Marine Le Pen – who on Monday stepped down as leader of the Front National to woo more voters – fared badly, gaining just under seven percent of the vote in Geneva and 8.5 percent in the rest of Romandie. That compares with 21.3 percent of French voters overall, a result that saw her beat Fillon into second place behind Macron.
While Macron is the overwhelming favourite to become French president on May 7th, should Le Pen pull off an unlikely victory Swiss politicians would be left reeling.
If the anti-EU, anti-immigration, protectionist Le Pen was president “it would be a disaster for France and Europe, and bad for Switzerland,” Socialist MP Martin Naef told 20 Minuten.
Her plan to hold a referendum to take France out of the EU would damage the “heart of Europe” and result in economic uncertainty that could harm Switzerland's trading relationship with its neighbour, he added.
A Le Pen presidency would have “more serious consequences” than Donald Trump's election in the US, said MP Christa Markwalder from the centre-right Liberal-Radical party.
It would be hard for Europe to cope with a potential ‘Frexit' alongside the existing Brexit negotiations, she said.
Even members of Switzerland's right-wing anti-immigration Swiss People's Party (SVP) are less than enamoured by the idea of a Le Pen presidency – with one even accusing the populist presidential candidate of being too left-wing.
Speaking to 20 Minuten, SVP MP Roland Rino Büchel said Le Pen was actually a left-winger who favoured state control, and that her policies were “not enough to bring France back on track”.
There are currently around 123,000 French nationals in Switzerland.