Metal prices dipped on Monday as the likelihood increased that U.S. lawmakers would fail to reach a budget deal to avoid going over the so-called fiscal cliff.
Lawmakers are increasingly skeptical about a possible deal because time is running out before the yearend deadline.
Failure to agree on a budget plan before Jan. 1 would lead to spending cuts and tax hikes that economists predict will push the economy back into recession.
In a quiet trading day before the Christmas holiday, copper for March delivery fell 2 cents to $3.55 a pound. March silver also fell, dropping 30 cents to $29.90 an ounce.
The price of copper moves with the outlook for global economic growth and has dropped almost 3 percent this month.
In other metals trading, gold for February was little changed at $1,659.50 an ounce. Platinum for January delivery fell $2 to $1,534.90 per ounce. Palladium for March delivery gained $2.25 to $684.55.
Crude oil futures prices ended lower on the New York Mercantile Exchange. The near-month contract for the benchmark grade fell 5 cents -- closing at $88.61 a barrel.
In other energy trading on the New York Mercantile Exchange natural gas for January lost 11 cents to finish at $3.4460 per 1,000 cubic feet. Heating oil fell 2 cents to end at $3.0022 a gallon. Wholesale gasoline for January rose 1.59 cents to finish at $2.7506 a gallon.
Agricultural commodities for March delivery were little changed. Wheat rose 2 cents to $7.94 a bushel. Corn gained 2 cents to $7.05. Soybeans fell 7 cents to $14.36.