On his first trip to Europe as US president, Barack Obama knows he faces a tough job convincing European allies to spend more to rescue the global economy.With two days to go, widely opposing views remain on the best way forward. French President Nicolas Sarkozy, who is seeking tighter financial regulation of the system, has already threatened to walk out if no reform commitments are made. That would be a blow to Obama and host Gordon brown want to spend their way out of recession. ‘‘We are putting money into the banking system to save the banks, not to save the bankers but to save peoples savings and peoples deposits and to make sure that we have a banking system that can serve the people,’‘ Brown said. But many European countries resisting calls to spend, see stricter rules as the best way to avoid future meltdowns. The EU Commission President José Manuel Barroso said: ‘‘One of the objectives, which was accepted in Washington, is that any institution or relevant entity cannot stay outside control or supervision. This is the principle I hope to see confirmed and consolidated in London.’‘ With fears of either a terrorist strike or anti-capitalist protests disrupting the G20, security in the British capital is tight. Many banks have already boarded up fearing they may become the target of peoples anger.