MONTPELIER, Vt. (AP) -- Vermont U.S. Sen. Bernie Sanders is joining colleagues from Maine and Minnesota in calling for a review of minimum federal dairy price supports, given sharply increasing expenses on the farm.

Sanders joined Sens. Olympia Snow and Susan Collins of Maine, as well as Al Franken of Minnesota in asking the U.S. Department of Agriculture to review its floor price for raw milk.

The senators point to rising production costs on the farm, including sharply higher prices for the corn that goes into animal feed. Corn reserves are at a 15 -year low, which is attributed to drought conditions in many areas.

The letter questions whether farmers can stay in business under such conditions.

Copyright 2012 The AP.