President Emmanuel Macron is the clear favorite in France's presidential race Sunday yet a big unknown factor may prove decisive: an unprecedented proportion of people say they are unsure who to vote for or don’t intend to vote at all, AP writes.

The pro-European centrist is still comfortably leading in the polls. His main challenger, far-right leader Marine Le Pen, appears on the rise in recent days. Both are in good position to reach the presidential runoff on 24 April, which would make them replay the 2017 election that Macron won handily.

There’s “no certainty,” Macron warned during his first big rally on Saturday near Paris.

“Don’t believe in polls or commentators who would sound definitive and tell you that ... the election is already done, that everything is going to be all right,” he told his supporters.

Scenarios for this year's runoff vote show that Le Pen has narrowed the gap with Macron significantly compared to 2017, when she lost.

Polls still put her behind Macron, but much closer, apparently showing the wisdom of her long-standing strategy to soften her rhetoric and image, allowing her to gain votes against Macron as well as support from the extreme right.