Hungary's parliament on Monday is expected to elect Constitutional Court head Tamas Sulyok as new president following the resignation of Katalin Novak, who caused outrage by pardoning a man convicted in a child abuse case.
The affair has turned into the biggest political crisis that nationalist Prime Minister Viktor Orban has faced since his return to power in 2010.
Orban ally Novak resigned as president earlier this month after it was revealed she had pardoned a convicted child abuser's accomplice.
Last week, ruling party Fidesz named Sulyok, 67, to replace Novak.
Sulyok is expected to be approved by parliament, where Fidesz' ruling coalition with the Christian Democratic KDNP holds a two-thirds majority.
The vote is scheduled to take place at 4:40 pm local time (1540 GMT) with the result expected to be announced later Monday, just after the votes are counted.
Little known to the broader public, Sulyok became a constitutional court judge in 2014 and, two years later, the court's head.
Around 3,000 people attended a Sunday protest by four opposition parties, calling for direct presidential elections.
The Novak scandal broke early this month when news site 444 revealed that she had pardoned the former deputy director of a children's home last year, on the eve of Pope Francis' visit.
The man was sentenced in 2022 to three years and four months in prison for helping to cover up his boss sexually abusing kids and adolescents there.
Tens of thousands of people have protested against the presidential pardon in Hungary, whose government has long campaigned on a pledge to protect children.
Orban likened the resignation of Novak, Hungary's first woman president, to a "nightmare", but stressed it was the right decision.