Khan's camp was increasingly confident, but it still appeared likely to fall short of a clear majority in the National Assembly. Full results are expected later in the morning.
As the counting continued, projections from four local TV channels put Khan's party ahead, estimating it would win between 107 and 120 seats of 272 elected seats available, while Sharif's outgoing ruling party was estimated at between 42 and 69. However, those projections were based on only about 20 percent of votes counted.
Khan's party spokesman, Fawad Chaudhry, showed confidence as the early projections were broadcast, saying in a tweet "Congratulations to the nation on a new Pakistan! Prime Minister Imran Khan".