WASHINGTON — The new Congress will be slightly more Democratic and more female, though House Republicans still hold a majority large enough to confront and confound President Obama as the nation grapples with a slow-moving economic recovery and record deficits.

Senate Democrats, once scrambling to save vulnerable incumbents and their tenuous numerical advantage, surprisingly gained a net of two seats as undecided races were settled Wednesday. The final results gave women a high-water mark of 20 in the 100-member chamber as Hawaii’s Mazie Hirono, Nebraska’s Deb Fischer, Elizabeth Warren of Massachusetts, Tammy Baldwin of Wisconsin, and Heidi Heitkamp of North Dakota were elected to join 15 returning female senators. Of the new female senators, all but Fischer are Democrats.