PARIS — In the climax of France’s presidential campaign, centrist President Emmanuel Macron and far-right contender Marine Le Pen will meet Wednesday evening in a one-on-one television debate that could prove decisive before Sunday’s runoff vote.

Both candidates have carefully prepared for the highly scrutinized debate that’s expected to last more than two hours.

Macron, 44, emerged ahead from the April 10 first round and is leading in opinion polls with a margin varying between 3 and 13 percentage points. But Le Pen, 53, has significantly narrowed the gap compared to the last presidential election five years ago, when she lost with 34% of the vote to Macron’s 66%.

In 2017, a similar debate struck a decisive blow to her campaign.

Le Pen had looked hesitant, seeking answers from notes piled up in front of her, and appeared to lose her composure at some point. She also made basic mistakes on several economic topics — which Macron immediately pounced on.

That proved disastrous for her image. Even in her own camp, she was criticized for being insufficiently prepared.

Meanwhile, the then 39-year-old Macron, despite his little political experience, seemed comfortable speaking about all kinds of issues and able to go deep into details in what appeared as a proof of seriousness.

Le Pen recently called the 2017 presidential debate the “biggest failure” of her political career.

This time, she has pledged to be better prepared, working “at home” with her closest advisers.

Both candidates need to broaden support before Sunday’s vote. Many French, especially on the left, say they still don’t know whether they will even go to the polls.

Le Pen is expected to appeal to those who have anti-Macron feelings, criticize his record and present her nationalist, anti-immigration stance as an alternative. She also aims at demonstrating that she has the stature of a potential president, and at promoting what she says are realistic proposals.

Macron, meanwhile, will advocate his pro-European views as the way to make France stronger in the world. He will seek to convince leftist voters that his pro-business stance shouldn’t deter them from choosing him.

In recent days, he acknowledged some would back him only to counter the far-right candidate.

“I want to convince women and men with diverse political points of view,” Macron said.