The two powerful central banks are "all in" as they act to give lawmakers more time to resolve problems in Europe and the United States, Mohamed El-Erian, who is also co-chief investment officer of Pacific Investment Management Co., said at a conference hosted by The Economist magazine.

In a wide-ranging speech that touched on Europe's debt crisis and suggested that a contraction in the U.S. government bond market is unlikely, El-Erian said he sees a 60 to 70 percent chance U.S. politicians will strike a "mini bargain" to avoid looming tax rises and spending cuts at year-end, known as the fiscal cliff.

Editor's Note: Economist Unapologetically Calls Out Bernanke, Obama for Mishandling Economy. See What They Did

Addressing the unprecedented monetary easing programs undertaken by both the Fed and the ECB, El-Erian said the heads of the two central banks — the ECB's Mario Draghi and Ben Bernanke of the Fed — recognize that any benefits from large-scale asset purchases carry risks.

"You should have no doubt — no doubt — the current leaderships of both central banks are committed and would likely do more before they do less," El-Erian said.

"It's very likely that they will be pushed to do more," he said, adding that the central banks alone cannot get the European and U.S. economies back on track.

"What's happening is you have the central banks trying to buy time, recognizing, as Chairman Bernanke said, that the benefits come with costs and risks."

Last month, both the European and U.S. central banks unveiled new bond buying plans, driving them deeper into uncharted policy territory. The ECB is trying to ease that region's debt crisis, while the Fed is trying to invigorate a weak economic recovery now more than three years after the Great Recession ended.

El-Erian lamented the "bickering and dithering" among U.S. and European politicians and cautioned that social unrest in places such as Greece could spread unless governments get some results.

He said Pimco, which oversees more than $1.82 trillion in assets, expects U.S. gross domestic product to grow around 1.5 percent to 2 percent over the next 12 months, while the firm expects Europe to contract by 1.0 percent to 1.5 percent, with quite pronounced differences among countries. China should have 6.5 percent to 7 percent annual GDP growth, he forecast.

The massive monetary stimulus programs, which include very low short-term interest rates, have depressed yields on U.S. government debt to near record lows, sparking concerns among investors that the trend will reverse sharply undercutting bond prices.

El-Erian said such a bond market contraction is possible, but unlikely.

"We're likely to see range-bound interest rates for a while still," he added.

Editor's Note: Economist Unapologetically Calls Out Bernanke, Obama for Mishandling Economy. See What They Did