Leaders will also back a huge 315-billion-euro ($380-billion) investment plan unveiled last month by new European Commission President Jean-Claude Juncker -- although hard cash is expected to be lacking to help kickstart Europe's economy.
"The Russian economic situation will be in everyone's minds," a European diplomat said, after a month that has seen Russia spend heavily to stop the collapse of the ruble triggered by falling oil prices and sanctions imposed by Brussels and Washington.
Tusk -- who on December 1 took up his duties as president of the European Council grouping the 28 EU member states -- has set aside talks on a "strategy" for Moscow, several European sources said.
No new sanctions will be decided at the summit in Brussels as the EU "is not in a hardening mindset," one diplomat said, while another added: "We don't want to provoke Putin too much."
"We must pursue the political work," a French source said.
On Tuesday, French President Francois Hollande and German Chancellor Angela Merkel held a conference call with presidents Vladimir Putin of Russia and Petro Poroshenko of Ukraine, agreeing that peace talks to end months of bloody rebellion in the east of the ex-Soviet republic should resume "as soon as possible".
The EU leaders, who want to tread a line between firmness and dialogue with Moscow, must reflect on how to follow up on the heavy sanctions agreed over the summer after the shooting down of Malaysia Airlines flight MH17, informs Report citing AFP.
"Everybody agrees that the sanctions have an impact but that they are not an end in themselves," a European source said, stressing that Russia has not changed its policy one bit on Ukraine.
Western powers have repeatedly accused Russia of stoking the Ukraine crisis, which has killed at least 4,700 people and displaced close to one million, by supplying weapons and troops to the rebels -- Moscow denies this.
Tusk said: "The crisis in Ukraine remains a serious concern.... It is therefore important that we come out of this meeting with a clear political message."