Ukraine’s European allies also believe there could be a small window to force Putin to the negotiating table, with his troops’ advances stalled, Russia’s air defences weakened and the economy on unsteady ground.
The talks on Sunday will be attended by Sir Keir Starmer, the Prime Minister, France’s Emmanuel Macron and Germany’s Friedrich Merz.
They will consider how to put further Western pressure on Russia and best support Ukraine if the war continues.
The Telegraph has previously reported on how Mr Zelensky now sees the E3, an unofficial security alliance of Europe’s largest countries, as a potential vehicle for reinvigorating the peace process.
Alternatives to Donald Trump
Kyiv is looking for alternatives to Donald Trump, who has made ending the war between Ukraine and Russia a key objective of his presidency, but has recently been sidetracked by his own conflict with Iran.
It is not clear whether the Europeans will be able to assume the US president’s role as a mediator given their ongoing support for Ukraine.
But they do have diplomatic channels between their own capitals and Moscow which could be used to ferry further messages from Mr Zelensky to Putin.
Both leaders have long claimed that they are willing to end the war, but differences over how it comes to a finish have dashed any hopes of a ceasefire.
The Kremlin chief insists that Ukraine must surrender the entirety of the eastern Donbas regions, including parts not yet occupied by Russian forces, as the price for peace.
In his open letter, Mr Zelensky reiterated that he would agree to an immediate truce along the current front lines of the conflict.