WASHINGTON _ The hour was growing late one March night and still neither party knew who had won a key special election in Pennsylvania, where only a few thousand votes separated the candidates. So Dan Sena _ executive director of the Democratic Congressional Campaign Committee _ turned to his chief number-cruncher for answers.
He handed her a note that showed how many absentee ballots each county had yet to count in the race between Democrat Conor Lamb and Republican Rick Saccone.
"I took the Post-It note, and with some number-crunching and math, found we would probably gain 300 votes," Claire Low, the DCCC's targeting and analytics director, would say months later.
