The Conference on the Future of Europe officially closes on Monday, ending a multi-year process that saw EU lawmakers consult citizens from across member states to see how to improve the European Union.
European Parliament President Roberta Metsola, European Commission President Ursula von der Leyen and current French President Emanuel Macron, whose country is currently presiding over the European Council, are all expected to speak.
A citizen consultation exercise resulted in over 300 recommended changes, combined into 49 proposals. MEPs have endorsed a rewrite of EU treaties to introduce those changes.
One idea is qualified majority voting, advanced by Macron and Italy's president Mario Draghi, to streamline decision-making.
That proposal is likely to face resistance from small member states like Malta, as it would render their veto less valuable.
An arguably less divisive proposal is to bring member states closer together in health matters. The EU jointly procured vaccines during the COVID-19 pandemic and the initiative is considered to be a success.
Another proposal is to grant more powers to the European Commission over areas jealously guarded by national governments, such as defence.
EU officials said the list of proposals - to be formally handed to Macron on Monday - would be assessed, but it was too early to say whether any of those retained would require a treaty overhaul.
One EU diplomat said: "More than 90 per cent of the proposals can be implemented below the threshold of treaty changes."
Other EU countries said to back treaty change are Spain, Belgium, the Netherlands and Luxembourg.
Analysts cautioned, though, that those against - small EU states that would rue losing their veto - would likely initially keep quiet.
If a majority of EU member states decided treaty change was needed, there could be a vote in the European Council that would lead to negotiations.
"We should be able to get the simple majority in council for that," another EU diplomat said.
Any resulting text would require all 27 EU countries' ratification or approval.
Attempts have been made before to reform the EU, not always successfully.
In 1992, Danish voters rejected the Maastricht Treaty, the modern EU's founding text, only to approve it a year later after their government negotiated opt-outs in sensitive policy areas.
In 2005, voters in France and the Netherlands rejected a treaty that would have brought in a formal EU constitution.