The proposal would create a two-tier system—one for those who directly invest with a mutual fund, and another for those that invest through intermediaries, such as the typical retirement plan participant, say opponents.

"The increase in January's PPI—which rose far more than the estimates, erasing last month's decline—moderates expectations for disinflation over the year ahead."

If the Fed had to set its inflation target today, it would choose 3% or 4%, rather than 2%, but "it is very difficult to change a target when you have missed it for so long. ... The minute you do that, your credibility is hit even harder."