The Czech prime minister and the European Commission president will meet on Tuesday to swap ideas on how to push the Lisbon Treaty over the finish line.Commission spokesman Johannes Laitenberger indicated they will be taking it one step at a time. “At this stage, what is needed is a first and foremost a clarification of the possible intentions of the Czech Republic,” he said. The last remaining signature that would get the Treaty up and running belongs to Czech president Vaclav Klaus. But he said only last week that he wants a derogation added to the Charter of Fundamental Rights, which would be binding once the Treaty is in force. Only then will he put pen to paper. Specifically he wants a guarantee that ethnic Germans expelled from Czechoslovakia after World War Two will not be able to make a legal claim to property confiscated from them by the Czechs. But even if Klaus signs the Treaty may run into another obstacle just around the corner. British Conservative opposition leader David Cameron has long demanded a referendum on the Treaty. His party is in a strong position to win next year’s election, by which time the Treaty may well be in force. But even if it is, Cameron has promised he will “not let matters rest there.” Once again, the Treaty will have to cross that bridge if and when it comes to it, but the ratification by Poland’s eurosceptic president on Saturday may give the text the momentum it needs to clear the final hurdle to ratification in Prague.