They expected that George A. Amedore Jr., a state assemblyman whose family has a successful home-building business in the capital region, would have no trouble making the jump to the Legislature’s upper house. Democrats sued to block the creation of the seat, but failed. Yet on Friday, 73 days after Election Day, Mr. Amedore conceded defeat to a little-known opponent: Cecilia F. Tkaczyk, a Democrat who, in addition to serving as vice president of the local school board, is also the vice president of the Golden Fleece Spinners and Weavers Guild. Ms. Tkaczyk (pronounced KAT-chik) was ahead by 18 votes — out of more than 126,000 cast — after a batch of contested ballots was counted in Ulster and Albany Counties. (Another uncounted ballot was found in Montgomery County, but it remains unclear whether it will be counted.) “No one believed our campaign had a chance in a district hand-carved by Republicans,” she said, “and yet the power of good ideas and a strong campaign proved itself.” Ms. Tkaczyk, from Schenectady County, is a third-generation farmer, and among her hobbies is spinning wool from her flock of Jacob sheep. She, unlike Mr. Amedore, also favors putting in place a system of public financing for state elections; supporters of election reform, including Jonathan Soros, a son of the billionaire financier George Soros, poured money into an independent-expenditure campaign supporting her. “She ran a great race and was a great candidate,” Jonathan Soros said. “Voters want this reform, and they’re actually willing to vote on it.” The race was for a seahorse-shaped district that stretches from the Mohawk Valley to the Hudson Valley. Ms. Tkaczyk, by trade a housing policy expert, emerged from Election Day with a narrow lead, but Mr. Amedore overtook her during a court-supervised counting of paper ballots, and a judge declared him the winner in late December. But an appeals court ruled last week that 99 additional disputed ballots should be tallied, and on Wednesday, the state’s highest court, the Court of Appeals, declined to hear an appeal, allowing the ballot-counting to proceed. “It was especially gratifying for the school board member and farmer to defeat the exceedingly wealthy assemblyman for whom the district was tailor-made,” said Dan Cantor, the executive director of the Working Families Party, which backed Ms. Tkaczyk. “David beat Goliath on this one, and that’s always a satisfying feeling for everyone involved.”