WASHINGTON (Reuters) - President Barack Obama held a video conference on Thursday with his counterparts from Germany, France and Britain to discuss the euro zone debt crisis and events in Libya, the White House said.

German Chancellor Angela Merkel and French President Nicolas Sarkozy "fully understand the urgency of the issues in the Eurozone and are working diligently to develop a comprehensive solution that addresses the challenge and which will be politically sustainable," the White House said.

France and Germany are still debating how to best strengthen a bailout fund for the common currency bloc to help it survive a roiling debt crisis, which has engulfed Greece and threatens to spread to other larger euro zone members.

European leaders must weigh their determination to save the euro with voters' anger over having to bail out the Greeks.

Obama has said he hopes a solution will be in place by a meeting of G20 leaders in France on November 3-4, and the White House reiterated the G20 meeting was a key date for the leaders.

"They agreed to continue to consult closely as they prepare to meet at the G-20 Summit in Cannes in early November," it said in a statement.

The leaders' video conference comes amid mounting concern in Washington that Europe's problems could sap the U.S. recovery. That impression was reinforced by a Thursday luncheon visit paid to Senate Democrats by Federal Reserve Chairman Ben Bernanke, who told them the Greek debt crisis was indeed having an impact on the struggling U.S. economy.

The major sticking point among euro zone heavyweights is over how to scale up the European Financial Stability Facility, a 440 billion euro ($600 billion) fund so far used to bail out Portugal and Ireland.

(Reporting by Laura MacInnis, Caren Bohan and Alister Bull; editing by Sandra Maler and Eric Beech)