Though they seemed likely to retain House control, their performance was an unexpected disappointment for the party, which hoped for modest gains of perhaps 15 seats.
Democrats control the House 232-197, with five open seats and one independent.
By retaining House control, Democrats would mark only the second time in a quarter century that they've led the chamber for two consecutive two-year Congresses.
She declared that Democrats had won the House majority, which seemed highly likely but hadn’t been officially declared by The Associated Press.
“House Republicans have outperformed all expectations," said Dan Conston, who heads the Congressional Leadership Fund, a committee aligned with House GOP leaders that provides millions to Republican candidates.