MONTGOMERY, Ala. — Alabama officials on Thursday unhesitatingly pushed aside a legal challenge from Roy S. Moore and certified Doug Jones as the winner of this month’s Senate election.

The action, during a brief meeting at the State Capitol, was essentially the state’s final step before the seating of the first Democrat elected to the Senate from Alabama in a quarter century. It was also a swift rejection, by some of the state’s most powerful Republicans, of Mr. Moore’s complaint that he was the victim of “systematic voter fraud.”

Mr. Jones’s margin of victory was 21,924 votes, with more than 1.3 million ballots cast.

The certification leaves Mr. Moore, 70, a former chief justice of the Alabama Supreme Court whose campaign faltered partly because of allegations of sexual misconduct against teenage girls, with almost no avenues to derail Mr. Jones’s ascension to the Senate. The election aftermath followed a familiar pattern for Mr. Moore, who in the past has been eager to declare victories and pronounce grievances — but unwilling to concede defeats.

To this day, Republicans note, Mr. Moore has not conceded his losses in the 2006 or 2010 Republican primaries for governor, and there is already speculation in Montgomery that he might run for governor or attorney general next year.