The White House said Saturday President Barack Obama has spoken separately by phone with French President Nicolas Sarkozy and German Chancellor Angela Merkel about developments in Europe's economic crisis. In the calls, Obama welcomed the continued leadership of Sarkozy and Merkel in addressing the challenges facing countries in Europe that use the euro as a common currency. The calls came after Italy promised to push for a constitutional amendment requiring the government to balance its budget as Rome sought to assure investors its finances are sound. Worries are spreading across the Eurozone that Italy may follow Greece, Ireland and Portugal in seeking financial help. The White House said Obama also discussed violence in Syria with Merkel and Sarkozy.