(Reuters) - A Virginia judge on Wednesday ordered an independent candidate in a key congressional contest removed from November’s ballot, citing invalid signatures gathered with assistance from staffers for the incumbent Republican.

Judge Gregory Rupe of the Richmond City Circuit Court ruled that Shaun Brown should be taken off from the Nov. 6 ballot in Virginia’s 2nd congressional district, which includes Virginia Beach, the most populous city in the state.

The race is one of several in the state that could help determine control of Congress in November. Democrats are looking to pick up 23 seats to win control of the U.S. House of Representatives and derail much of Republican President Donald Trump’s legislative agenda.

U.S. Representative Scott Taylor is seeking re-election in the district, which leans slightly more conservative than the country as a whole but is considered a pickup opportunity for Democrats.

Brown ran as a Democrat for the seat in 2016, losing to Taylor, and had sought the Democratic Party’s nomination again this year before dropping out of that race.

The effort to put Brown on the ballot as an independent candidate - which could have siphoned votes from the Democratic nominee, Elaine Luria - was boosted by Taylor’s campaign staffers, according to published reports. Taylor told the Washington Post in August that he knew staffers were collecting signatures for Brown, but that he did not direct the effort.

Taylor’s campaign did not immediately comment.

Virginia’s Democratic Party sued the state in August, seeking Brown’s removal from the ballot. Local media reports found that signatures on Brown’s petition included residents who said they did not sign, as well as names of deceased residents.

Brown submitted more than 2,500 signatures, according to the Democratic Party’s lawsuit, exceeding the required 1,000, but the judge determined that fewer than 1,000 were valid.

“Today’s decision is a win for the integrity of our elections,” Virginia Democratic Party communications director Jake Rubenstein said in a statement.

Brown’s attorney, James Ellenson, was not immediately available for comment.