WASHINGTON — U.S. employers added 155,000 jobs in December, a steady gain that shows hiring held up during the tense negotiations to resolve the fiscal cliff.

The solid job growth wasn’t enough to push down the unemployment rate, which remained 7.8 percent last month, the Labor Department said today. The rate for November was revised up from an initially reported 7.7 percent.

The government also said hiring was stronger in the previous month than first thought. November’s job gains were revised up 15,000 to 161,000. October’s increase was nearly unchanged at 137,000.

The “gain is perhaps better than it looks given that firms were probably nervous about adding workers with the fiscal cliff looming,” said Paul Ashworth, an economist at Capital Economics.

Robust hiring in manufacturing and construction fueled the December job gains. Construction firms added 30,000, the most in 15 months. That increase likely reflected hiring needed to rebuild after Superstorm Sandy and also gains in home building that have contributed to a housing recovery.

Manufacturers added 25,000 jobs, the most in nine months.