WASHINGTON — The top leaders in both parties on the House and Senate Agriculture committees agreed to a one-year extension of the 2008 farm bill that expired in October, a move that would head off a possible doubling of milk prices next month.

Senate Agriculture Committee Chairman Debbie Stabenow indicated that the House could vote on it as early as Sunday evening. The agreement to extend current farm law until next October was reached as negotiators hit a snag on averting a broader fiscal cliff combination of higher taxes and spending cuts Jan. 1.

Agriculture Secretary Tom Vilsack said Americans faced the prospect of paying $7 for a gallon if the current dairy program lapsed and the gove