Orders to U.S. factories fell for a fourth straight month in November, with demand in a key category that signals business investment plans down for a third month.

The Commerce Department says factory orders dropped 0.7 percent in November after a similar 0.7 percent fall in October. The November weakness came from decreases in demand for primary metals, industrial machinery and military aircraft.

A closely watched category that serves as a proxy for business investment spending dropped 0.5 percent in November, the third straight decline, the longest stretch of weakness in this category since 2012.

Economists, however, remain optimistic that the drop in orders is a temporary soft patch and a stronger economy with increased consumer spending will trigger a rebound in demand in 2015.