Reto Francioni, the chief executive of the German exchange, was talking to Euronext shareholders yesterday about changing the terms of its offer to make it more attractive.
Euronext recommended last week that investors back an alternative merger proposal from the New York Stock Exchange.
Meanwhile, staff representatives on Deutsche Börse's supervisory board demanded an end to efforts to merge with Euronext, the operator of the Paris, Lisbon and Brussels exchanges and London's Liffe derivatives business.
Reuters reported that workers' representatives who hold seven of 21 seats on the supervisory board, wrote to Mr Francioni telling him to stop the negotiations with Euronext.
Mr Francioni declared "market integration would strengthen" and national policymakers would be brought closer together. He asked for Euronext to judge Deutsche Börse's proposal on the basis of cost savings, not politics.
On Wednesday, the French President, Jacques Chirac, said: "I favour the Franco-German solution for reasons of principle." The same day, Italy's Economy minister said the ideal outcome was a tie-up between Deutsche Börse, Euronext and Borsa Italiana.
Edgar Meister, a German central banker, and Jean-Claude Trichet, president of the European Central Bank, added their voices to growing calls for Euronext to take a European partner.