LONDON — Sadiq Khan will call for an end to British politicians’ “vow of silence” on the ill effects of leaving the EU as he tries to rally support ahead of this year’s London mayoral election.

In a speech on Thursday evening, the incumbent Labour mayor of London will accuse the Conservative government of “trying to will Brexit into a success” and “simply ignoring its impact” on the capital.

But while Khan’s remarks will explicitly call out the U.K. government’s own perceived failures, the intervention will also be seen as an attempt to distance the mayor from Labour’s own national leadership, which has presented itself as increasingly comfortable with life outside the European project.

Under Keir Starmer, Labour has said it wants to “make Brexit work” and has ruled out rejoining the EU’s single market or customs union, as well as reintroducing free movement.

However, Khan faces different electoral terrain to Starmer, with Remain-supporting London strongly in favor of membership of the bloc — unlike some areas of England’s north and midlands.

A new first-past-the-post electoral system for electing London’s mayor also leaves Khan potentially vulnerable to losing votes to the pro-European Liberal Democrats and Greens.

“No one wants to see a return to the division and deadlock that dominated our body politic for five long years,” Khan will tell business leaders in a speech at Mansion House in the City of London.

“However, the inescapable truth is that this unnecessarily hard-line version of Brexit is having a detrimental effect on our capital and country — at a time when we can least afford it.

“We can’t – in all good conscience – pretend that it isn’t hurting our people and harming our businesses. As Mayor of this great city, choosing not to say anything would be a dereliction of duty.”

The mayor is expected to cite research commissioned by City Hall suggesting the U.K. has two million fewer jobs thanks to its rupture with the EU, and that it has so far cost the British economy £140 billion.

Despite the ongoing effects of the divorce, the salience of Brexit as an issue has dropped dramatically among voters since the 2019 election.

In September 2019, a YouGov tracker poll found 73 percent of voters rated the EU as a top issue. By January 2024 that figure had fallen to just 14 percent.