A federal appeals court declined to stop a Virginia Republican from being sworn into the House of Delegates Wednesday over a mistake that threw an extremely close election into question.

The decision came just two hours before the convening of the legislature, where Republicans hold a narrow majority in both chambers after November's elections.

Republican Robert Thomas beat Democrat Joshua Cole in the Fredericksburg-area 28th District by 73 votes. But errors in voting data meant hundreds of people were assigned to the wrong legislative district. Four Democratic voters sued for Thomas to be blocked from taking office while a special election is held.

A federal judge in the Eastern District of Virginia concluded that the mistakes made in voter data and by poll workers on Election Day, while unfortunate, did not appear so widespread that Thomas should be blocked from taking his seat. The Democratic voters appealed to the U.S. Court of Appeals for the 4th Circuit.

A three-judge panel of the appeals court agreed unanimously, without explaining their decision.

Thomas took his oath of office in the House of Delegates, along with his colleagues.

"Today I was honored to take a seat in the oldest legislative body in the new world," Thomas said. "I took the oath of office with equal measures of awe and humility. I cannot thank the people of House District 28 enough for placing their trust in me to represent them. The path to Richmond was full of challenges, but I am happy to finally get to work."

Cole's campaign manager, Eric Sundberg, said Wednesday that Cole plans to run again for the seat in 2019.

"We're disappointed, of course, with the decision not to hear the appeal," Sundberg said. "But . . . we don't think the issue should be left to sit, even if it's not addressed right now."

Sundberg said he hoped Thomas will "pursue the issue and do what's right for the people of the 28th District."

Katie Baker, a spokeswoman for the House Democratic Caucus, called the election "irreparably tainted."

At least 86 voters, including some in a heavily Democratic precinct, were mistakenly issued ballots to vote in the neighboring House District 88, where the Republican won by a wide margin. And 61 voters in the 88th District, which tilts Republican, were mistakenly given ballots to vote in the 28th.

The Virginia NAACP weighed in Tuesday, saying in a court filing that letting the election results stand "will deny African American voters an opportunity to elect their candidate of choice."

Fredericksburg is nearly a quarter black, and two heavily Democratic precincts in the city were affected by the mistake.

Cole and Democratic activists held rallies during the week between Christmas and New Year's, framing the issue as a civil rights cause.

State officials, the state NAACP contended, "acted willfully to diminish the voices of District 28's African American voters."

Michael Matheson of the firm ThompsonMcMullan, representing local election officials, responded in his own filing that there was not "even a scintilla of evidence" of any willful attempt to disenfranchise voters, "much less one that is racially motivated."

Local election officials from the Fredericksburg area and the Republican Party of Virginia said the mistakes were garden variety and scattershot rather than systemic. They said the errors affected too small a percentage of voters to warrant a new election.

One of the plaintiffs, D.D. Lecky, said in court filings that when she tried to vote for Cole on Election Day and pointed to a map in her Fredericksburg polling place that showed she lived in the 28th District, officials then took the map down. But she told reporters last week that she thought that decision was made out of genuine belief that the map was wrong, not maliciousness.

Republicans now hold a 51-to-49 seat majority in the House of Delegates. Democrat Shelly Simonds announced Wednesday that she would not seek a recount in a tied race that was decided last week when state officials drew a name from a bowl, clearing the way for Republican David Yancey to take his seat.

Fenit Nirappil contributed to this report.