Jacque Patterson, a Democrat seeking an open D.C. Council seat, has been ousted from the April 26 ballot by election officials, dealing a grave blow to his campaign.

But the sole Republican, Patrick Mara, will remain, surviving a close call after officials questioned whether some of his petition signatures might have been forged.

Mara once appeared to be a shoo-in to appear on the special election ballot. He turned in 5,629 petition signatures; only 3,000 are required. But a series of challenges brought by supporters of his opponents, as well as the forgery concerns, caused the Board of Elections and Ethics to question a large portion of Mara’s signatures.

Still, the board ruled that 3,166 valid names remained, keeping him eligible for the ballot.

Patterson was not so lucky. The board upheld a determination that 1,191 of the 3,408 signatures that Patterson submitted were invalid, leaving him well short of the threshhold.

Earlier this month, Bandele McQueen, a supporter of Sekou Biddle, challenged petitions submitted by Mara, Patterson and a third candidate, Bryan Weaver. Lawrence Guyot, a supporter of candidate Joshua Lopez, also challenged Mara. (McQueen withdrew his challenge to Weaver on Monday.)

The board verified 2,447 of McQueen’s challenges to Mara signatures, while 302 of Guyot’s stood. Neither challenge by itself was enough to boot Mara, but while reviewing the other challenges, board staff identified 160 signatures submitted by Mara that “appear to be forgeries.”

But there weren’t enough to boot Mara — 136 of them were already disqualified through McQueen and Guyot’s challenges, and the remaining 24 weren’t enough to take Mara below 3,000.

What the board did not do was invalidate all of the signatures collected by persons alleged to have turned in forgeries. There is precedent for such a move: The BOEE, in the course of ruling on Mayor Anthony A. Williams’ disastrous 2002 re-election effort, tossed dozens of pages of clearly falsified names. But the board did not find that Mara’s petitions were “tainted by fraud or strong appearance of fraud,” as in the Williams case, warranting a mass disqualification.

The board, however, referred circulators who submitted “apparent forgeries” to authorities for further investigation.

Earlier Tuesday, Mara’s supporters raised objections to the challenge and told reporters they were prepared to petition the D.C. Court of Appeals to overturn an adverse ruling.

Charlie Spies, an attorney for Mara, and Paul Craney, executive director of the D.C. Republican Committee, accused elections officials of conspiring with Democratic insiders to deny Mara access to the ballot.

”What has become very clear is that the board is pulling out all the stops with a results-oriented process to find a way to knock Patrick Mara off the ballot,” Spies said.

But they presented little to support a conspiracy, except for evidence of a rushed and sloppy process. They denied there was any organized attempt to forge signatures, though Craney said that Mara had paid some of his circulators by the signature.

”When you pay people to collect signatures, some of them are going to get thrown out,” he said.

After the decision was released, Mara criticized the board for waiting till after 6:30 p.m. to release a decision that was due by law had been promised by close of business. “The inability to meet a simple deadline speaks to the board’s competence and reliability,” he said, adding that he was concerned that Mayor Vincent C. Gray (D) has not moved to appoint a non-Democrat to the board.

As for Patterson, the board summarily dismissed his objection to the form of McQueen’s complaint — that the challenge wasn’t valid because it listed page and line numbers for each questioned signature rather than the name itself.

BOEE member Charles Lowery rejected that line of argument, holding that McQueen’s method was precise enough to satisfy the law.

”The challenge was not a Rubik’s Cube as [Patterson] asserts,” Lowery wrote. “The Registrar had no difficulty discerning which signatures were challenged and the specific defects alleged with the key provided, and she conducted her determination in the ordinary course.”

Patterson criticized Biddle for sponsoring the challenged that knocked him from the ballot. He said Tuesday evening that he will decide whether to appeal the decision on Wednesday morning.

UPDATE, 3/16: The board’s decision was not due by law at close of business, said BOEE spokeswoman Alysoun McLaughlin, though its staff had said it would be ready by that time. Late Tuesday, a board member asked for additional revisions to the final opinions, she said, delaying the release.