The Greek EU presidency arranged the Brussels talks to heal the rift but many fear the meeting will only throw the spotlight on how torn the West is over military action.
The continuing wrangle at NATO over reinforcing Turkey's defences in case of conflict has done nothing to help the mood.
And the latest report from UN chief weapons inspector Hans Blix has presented the European leaders with nothing to help resolve their fundamental political differences.
On the eve of the EU summit, Greece warned failure to reach a consensus on European policy towards Iraq would plunge the union into "deep crisis".
There are grave doubts whether, with frustration and confusion mounting in national capitals, anything more than token unity can be achieved.
NATO's credibility has been badly damaged by the Iraq crisis, with alliance Secretary-General George Robertson frantically battling over the weekend to break a deadlock which has left Washington seething.
Talks continued at NATO headquarters last night, with France, Germany and Belgium still blocking a US request to send military hardware to assist Turkey in case military intervention triggers Iraqi retaliation against the nearest alliance member state.
Belgium moved closer to compromise during the day but efforts foundered over a form of words emphasising that shoring up Turkish security is purely defensive and does not amount to an aggressive military build-up.
"We've been saying that for weeks" said one angry senior diplomatic source at Nato headquarters. "That is the whole point to prepare to support one of our number facing a possible external threat."
Similar frustrations will be on display down the road at the EU summit, with France and Germany leading Belgium, Luxembourg, Greece and Austria in strong opposition to backing Washington in the drive to war.
Only four member states Spain, Italy, Denmark and the Netherlands are openly lining up behind Britain in support of President George Bush's push to go to war.
The remaining four, including Ireland, are sitting on the fence, anxious not to offend the Americans but deeply worried about the military build-up against Iraq. It will be hard to get an EU accord on anything but the blandest of sentiments, skirting round the contentious question of whether it is right to launch military action to unseat Saddam Hussein.
"EU leaders should lock themselves in a room at their emergency summit and not come out until they have put aside their differences and forged a common approach to the Iraqi crisis" said Liberal Democrat MEP Graham Watson. The problem is France and Germany are seizing on Dr Blix's report as reinforcing the value of continuing weapons inspections, while Britain is emphasising the report's confirmation that Iraq is in "material breach" of UN resolutions.