BRUSSELS — Four European commissioners on Wednesday blasted the European Parliament for failing to approve a bill to fight online child sexual abuse material.

The four commissioners said children will be left vulnerable to exploitation if the bill doesn’t pass soon, in a letter obtained by POLITICO ahead of a last-ditch attempt to reach a solution on Thursday.

Parliamentarians on Thursday will vote on a bill that would extend a temporary EU regime allowing tech platforms to scan their services for child sexual abuse material (CSAM), after EU negotiators failed twice this month to land a political deal to extend the law. The rules expire on April 3, at which point scanning for the content would become illegal in Europe.

Having a gap in enforcement would have “immediate and severe” consequences including “reduced detection, fewer reports to law enforcement, and greater impunity for perpetrators,” the commissioners said in their letter. “As lawmakers, we have a duty to act.”

The controversy shows how political tricky the issue of online child protection is in Europe. On one side, child rights groups and security authorities have pushed for stricter policing of online spaces. On the other, privacy rights activists have warned it opens the door to mass surveillance of online communication on the other.

The center-right European People’s Party (EPP) is leading a Hail Mary attempt to extend the rules. It filed an amendment last Friday that would overrule Parliament’s earlier position and align it with what national governments and the Commission want.

The center-right proposal needs the support from enough centrist and center-left lawmakers in order to win approval. But centrist and left-leaning lawmakers feel it would weaken privacy and massively undermine Parliament’s negotiating position in the talks with Council.

The European Commission’s letter was signed by tech chief Henna Virkkunen, Internal Affairs Commissioner Magnus Brunner, Justice Commissioner Michael McGrath and youth chief Glenn Micallef.

“As parents, lawmakers and Europeans, we cannot let this deadline slide without renewing our plea to you … to act before it is too late,” the commissioners wrote.

They urged Parliament leaders to share the letter with members of their groups and “allow [members of Parliament] each to take their individual responsibility in this matter ahead of the plenary vote tomorrow.”

The temporary rules to scan for child sexual abuse material include an exemption to the bloc’s privacy rules. The regime allows companies like Meta, Microsoft and Google to voluntarily scan their platforms to identify millions of items of illegal content without breaking privacy law. The rules are a workaround, aimed to keep scanning going while the European Union negotiates another, permanent law to fight child sexual abuse online — but those negotiations have also been stuck a deadlock.

Large platforms Meta (which owns WhatsApp, Facebook and Instagram), TikTok, Snapchat, Google, Microsoft and LinkedIn (owned by Microsoft) said in a joint statement last week that the EU’s inability to reach a deal was “irresponsible.”

“Failure to act will reduce the legal clarity that has enabled companies for nearly 20 years to voluntarily detect and report known child sexual abuse material (CSAM) in interpersonal communication services,” the tech giants said.

Mathieu Pollet and Ellen O’Regan contributed reporting.

This article was updated to include new developments.