In Washington, financial speculators have fat targets on their backs.

They are being blamed for high gas prices, soaring grocery bills and volatile commodity markets, and lawmakers are lashing out at market regulators for not cracking down on them more vigorously.

“You study it, but you don’t act against this incredible increase in speculation,” Senator Carl Levin, Democrat of Michigan, complained to a senior official of the Commodity Futures Trading Commission at a recent Senate hearing. “Unless the C.F.T.C. is going to act against speculation, we don’t have a cop on the beat.”

Just this week, Senator Joseph I. Lieberman, the Connecticut independent, said he was working on a proposal to ban large institutional investors from the commodity markets entirely. The same day, the Bush administration endorsed another Senate proposal to create a new federal interagency task force to investigate commodity speculation. At least four public hearings have explored the topic in just the last two months, and Senator Lieberman will hold another session on June 24.

Although it is common in tough financial times to blame the speculators, this escalating hostility toward them is starting to worry people with years of knowledge about how commodity markets work. Because without speculators, they say, these markets do not work at all.