German Chancellor Angela Merkel and French President Francois Hollande are meeting Russia’s Vladimir Putin to try to end escalating fighting in Ukraine.
Mr Hollande and Mrs Merkel are taking to Moscow a peace proposal crafted in the Ukrainian capital Kiev on Thursday, but details have not been released.
Meanwhile a truce has allowed civilians to leave Debaltseve, at the heart of the latest fighting in eastern Ukraine.
Russia is accused of arming pro-Russian separatists – a claim it denies.
The Kremlin also rejects claims by Ukraine and the West that its regular troops are fighting alongside the rebels in the eastern Donetsk and Luhansk regions.
Clashes have left nearly 5,400 people dead since April, the UN says.
A September ceasefire, signed in Minsk in Belarus, has failed to stop the violence. Since then the rebels have seized more ground, raising alarm in Kiev and among Ukraine’s backers.
Analysis: David Stern, BBC News, Kiev
This may not be the last attempt to try to find a peaceful solution to the hostilities in eastern Ukraine, but there is a sense that the door is closing fast.
On Thursday German Foreign Minister Frank-Walter Steinmeier said the West must see if there was still a chance to reach a settlement, before there was “complete loss of control” over the conflict. France’s President Francois Hollande has said diplomacy could not “go on indefinitely.”
That Angela Merkel is travelling to Moscow can be seen as a positive sign – the German chancellor said she wouldn’t meet Vladimir Putin without the concrete prospect of progress.
But the roadblocks to a final peace – or even a lasting ceasefire – are formidable and many. Not least is the low level of trust among Ukrainian and Western officials for any promises coming from the Kremlin.