France began voting in a presidential runoff election Sunday in a race between incumbent Emmanuel Macron and far-right politician Marine Le Pen.

Macron is in pole position to win reelection for a second five-year term in the country’s presidential runoff, yet his lead over Le Pen depends on one major uncertainty: voters who could decide to stay home.

A Macron victory in this vote — which could have far-reaching repercussions for Europe’s future direction and Western efforts to stop the war in Ukraine — would make him the first French president in 20 years to win a second term.

All opinion polls in recent days converge toward a win for the 44-year-old pro-European centrist — yet the margin over his 53-year-old nationalist rival varies broadly, from 6 to 15 percentage points, depending on the poll. Polls also forecast a possibly record-high number of people who will either cast a blank vote or not vote at all.

Both candidates are trying to court the 7.7 million votes of a leftist candidate defeated in the first vote. Polling stations opened at 8 a.m. on Sunday and close at 7 p.m. in most places, apart from big cities who have chosen to keep stations open until 8 p.m.

For many who voted for left-wing candidates in the first round April 10, this runoff vote presents a unpalatable choice between a nationalist in Le Pen, and a president who some feel has veered to the right during his first term. The outcome could depend on how left-wing voters make up their minds: between backing Macron or abstaining and leaving him to fend for himself against Le Pen.