Janet Yellen, dubbed “Ms. QE Infinity” by some wags because of her support for printing money to create jobs, and her willingness to pierce the Fed’s long-held 2 percent annual inflation ceiling, will have more to worry about than monetary policy when she steps into Ben Bernanke’s ample shoes on February 1. There is the small matter of regulating the nation’s banks, a chore made difficult for her by two unrelated facts.

The first is that she does not have as firm a theoretical grasp of regulatory issues as she does of monetary policy. Second, her relations with fellow Fed governor Daniel Tarullo are reported to be more than a little fraught. And Tarullo, a one-time Obama campaign adviser still close to the White House, has primary responsibility for the Fed’s bank-regulation program. The differences between Tarullo and Yellen is not doctrinal – both favor aggressive regulation – but personal, which unfortunately often proves to be the more difficult to overcome.