Starting from today, the G20 will face a real challenge in getting a global deal that includes America during the weekend, after U.S. President Barack Obama’s surprised bank restructuring plan jeopardized a hard-won international consensus.

The U.S. leader stunned global markets and policymakers last month when he unilaterally proposed curbing the size and trading activities of banks. The plan, which has cross-border implications, has raised concerns that a global deal on regulation is being hijacked by populist national interests.

Four of the G7 countries that will meet today on Friday and Saturday in the Arctic Canadian town of Iqaluit - France, Germany, Britain and host Canada - have signaled they do not believe such radical restructuring of banks is necessary.

European countries are against Obama’s new policy as they believe that it will affect the rest of the world’s economies negatively. In other words, Obama favored internal interests against international interests.

Moreover, they fear that the U.S. plan — even though there is no guarantee a fractious Congress will adopt it — will encourage other countries to promote their own national interests, creating potential loopholes for banks to exploit.

Britain alarmed some countries by unilaterally introducing a new liquidity regime for domestic and foreign banks before a global deal had been reached.

“It is important where possible to reach international agreement on regulatory reform, but it might be the case that we have to act in advance of international agreements where it is right to do so, particularly given the size of the financial services sector in the UK,” said Mark Hoban, the party’s financial services spokesman.

Obama’s plan is not the only chink emerging in the G20 blueprint. Britain and France also slapped a windfall tax on bonuses, a step other G20 countries have yet to copy. G20 countries face pressure to show that the world’s regulatory blueprint remains intact amid the economic crisis.