The euro could take a "swan dive" if the two extremist candidates advance to the second round of the French election, currency expert Boris Schlossberg told CNBC on Friday.
And right now, the race is a "complete wild card," with about 40 percent of voters undecided, he pointed out. The first round of the election is set for Sunday.
Four candidates are making a bid for the presidency. Former Economy Minister Emmanuel Macron and mainstream conservative Francois Fillon are the two centrist candidates. Far-right Marine Le Pen and far-left Jean-Luc Melenchon have both indicated they are willing to take France out of the European Union.
"Any kind of serious contention that Le Pen wins or, the worst-case scenario, if we have Melenchon and Le Pen — the far right, far left — the only choice for France, could take the euro down to parity very quickly," Schlossberg, managing director of FX strategy at BK Asset Management, said in an interview with "Closing Bell."
However, at the moment the market is anticipating a likely runoff between Macron and Le Pen, said Shaun Osborne, chief currency strategist at Scotia Bank.
He believes if that happens, the euro could rally up to 1.09. If it ends up a contest between the two extremist candidates, he thinks the euro could fall as low as 1.04.
"This is one big hurdle for the euro. There are more coming this year," Osborne warned, pointing to the upcoming elections in German and Italy.
Schlossberg agreed that Italy is also important, noting that there is a tremendous amount of populist resistance to the euro there as well.
"The key question is can they really hold it together at this point. Can the union come together and create a more viable economic society for the rest of the European Union at this point," he said.
"It's not so much even that [Le Pen] may win, it's a question of how big that whole populist vote is and how much discontent there is in the euro zone."
—CNBC's Crystal Lau contributed to this report.