Long after most Coloradans — including the candidates and their supporters — had gone to bed, returns from Denver and Boulder moved Bennet past Buck and into the lead, 47.5 percent to 47.1 percent.

A recount would be required if the difference between the two candidates’ vote totals is less than one-half of 1 percent of the highest vote total, or about 3,900 votes based on current tallies.

Bennet leads by nearly 7,000 votes with an estimated 30,000 still to be counted in Boulder County.