Conservative leader David Cameron is set to spell out his vision of the future European Union - one that "does things that matter".
His message to the party is that he has no intention of leading a Tory retreat from the EU.
And his message to the public is that he will back the national interest and push for decisions people want in the EU on climate change and CO2 emissions, strengthening a competitive economy, cutting red tape and tackling poverty.
Mr Cameron's defining speech on the EU comes in Brussels at the first conference of the Movement for European Reform, which he launched last year with the Tory's sister party in the Czech Republic, the ODS.
Mr Cameron will call for a new EU approach, replacing integration and institutional navel-gazing with more co-operation between nation states.
His speech this afternoon to an audience of European politicians, academics and business leaders attacks Labour's stance on Europe, accusing the Government of indecision on the becalmed constitution, and "posturing" on EU policy.
Mr Cameron will say: "There are two ways that a British politician can speak in Europe. One way is to posture for the TV cameras back home and boast of your determination to stand up for the national interest. And then, later - inevitably - to agree to whatever proposal is on the table.
The Tory leader says his approach to EU negotiations generally will be different.
"I believe that the best way to pursue your national interest is not to posture - but to persuade. I will be polite, but solid and consistent. I will work to create a flexible Europe by building alliances with those who share our interests and our ideas," he says.
Europe minister Geoff Hoon said Mr Cameron was copying Labour's EU reform programme, saying: "I'm not quite sure which horse Mr Cameron is riding at the moment: is he eurosceptic or is he changing horses to become more sympathetic to the Government's EU programme?"