French president Emmanuel Macron and German Chancellor Angela Merkel are to meet in Estonia's capital Tallinn today, ahead of a two-day summit involving all 28 EU leaders.
Their meeting comes just days after Mr Macron set out plans for ambitious EU reforms, which will be high on the summit agenda.
Mr Macron sees Mrs Merkel's backing as crucial for his plans to shake up the EU as it prepares for Britain's departure.
He set out his vision for a rebooted Europe in a speech at the Sorbonne university in Paris on Tuesday, describing the EU at present as "too weak, too slow, too inefficient".
His proposals include a eurozone finance minister, budget and parliament.
He called for European countries to go much further in linking their economies, governments and armies, proposing a joint defence force as well as new agencies for asylum and innovation and ideas for tax reform.
The meeting in Tallinn comes ahead of a dinner later in the day where all 28 EU leaders will be given an open forum for a "frank and informal" discussion, according to EU President Donald Tusk.
