Federal Reserve Chairman Ben Bernanke is expected to announce Wednesday plans to purchase more government bonds. Tuesday, Bernanke was opening a two-day meeting where he will help craft the plan he hopes will further drive down interest rates on mortgages and other loans.

But Fed officials have already driven rates to super-low levels. And still, the state of the economy remains dismal.

Yet anticipation of the new program has helped to bolster equity prices and lower long-term mortgage rates, according to former Federal Reserve vice chairman Donald Kohn.

In an interview with The Wall Street Journal, Kohn said, “I don’t think that anything they will end up doing will instantly and by a huge amount turn the economy around. But it could help on the margin in what is an unsatisfactory situation. If they go ahead and do it, I expect some benefit.”

Wall Street investors and many economists are anticipating the Fed will settle on $500 billion in bond purchases. Anything less could disappoint bond and stock traders, as well as send interest rates up and stock prices down.

More than a year after the recession ended, the economy has failed to generate a robust rebound. The jobless rate continues to stand at 9.6 percent. It’s been at least 9.5 percent for 14 months, the longest stretch since the Great Depression.

The “slack” in the economy—factories running below capacity and companies limiting hiring—has kept inflation historically low. In the 12 months that ended in September, consumer prices rose just 1.1 percent.

Bernanke has said the Fed would like to see inflation closer to 2 percent, for fear super-low inflation will turn into deflation. Yet, the notion of letting inflation run higher makes some Fed members queasy.

Thomas Hoenig, president of the Federal Reserve Bank of Kansas City, argues that another round of Fed action could lead to too-high inflation and new speculative asset bubbles. At each meeting this year, Hoenig has opposed the Fed’s pledges to keep rates at record lows and other efforts to energize the economy.

While Fed officials acknowledge that the risk of deflation is small, an outbreak could be devastating, they say.

The Associated Press contributed to this report.

For more, see Lee Wishing’s Commentary “Controlling the Fed.”