The D.C. Board of Elections will allow further scrutiny this weekend of petition signatures that D.C. Council member Michael A. Brown’s campaign submitted to qualify for the November ballot, adding new uncertainty to his campaign.

At a hearing Friday, election officials preliminarily concluded that Brown (I-At Large) submitted 3,146 valid signatures, barely meeting the threshold of 3,000 from registered voters.

But council candidate David Grosso and longtime city activist Dorothy Brizill, who are challenging Brown’s petitions, say they discovered flaws in the board’s work. Election officials granted the challengers’ request to have additional time to review Brown’s petitions. Grosso and Brizill say they are confident that the filings still contain dozens or hundreds of invalid or forged signatures.

The Brown campaign has denied any wrongdoing, saying the fraud allegations are without merit and defamatory. But the board agreed to allow Grosso, an independent running against Brown, and Brizill to compare Brown’s signatures against voter registration records over the weekend.

“To me, this is the bedrock of the Democratic process,” Brizill said. “This is not [Brown’s] first time at the rodeo. He’s been a candidate before.”

Councilmember Michael Brown is seen at a 2011 event. (Michael Temchine/For The Washington Post)

The board will also consider a request from Brizill that more than a dozen Brown staff members and campaign volunteers be subpoenaed to testify as part of the petition challenge. Brizill and her husband, Gary Imhoff, have alleged that witness testimony may bolster their argument that some of Brown’s signatures were forged.

Brizill and Imhoff, who launched the D.C. Watch blog, filed a complaint Aug. 20 that cited cases in which “the printed name bears no resemblance to the signature” or multiple signatures appeared to be “written by the same individual in the same hand.”

In a preliminary ruling last week, the board’s registrar and assistant counsel determined that Brown appeared to have narrowly made the ballot with about 3,300 valid signatures from registered voters. Brizill and Grosso protested that decision.

On Friday, after the second review, election officials concluded that Brown had 3,146 valid signatures. The board met to decide on the separate complaint by Brizill, Imhoff and Grosso.

Brown did not attend the hearing, but his attorney, Thorn Pozen, appeared annoyed that the board was allowing the challengers to keep pressing their case. Pozen accused Brizill and Grosso of going “on a fishing expedition” that lacked evidence of wrongdoing.

“There really isn’t anything these people are going to come in and say that they have not already attested to under penalty of perjury,” said Pozen, referring to the oath taken by candidate petition circulators.

The board is expected to rule on the issue Monday.

In an interview, Grosso said Brown’s signature count has been falling, leaving him perilously close to being kicked off the ballot.

“If he had done the hard work at the beginning to get the signatures, we would not be in this problem,” Grosso said. “Every time we look at the numbers, it gets further and further invalidated.”

L. Asher Corson, a spokesman for Brown, countered that Grosso and Brizill are wasting election officials’ time. He said that Grosso turned in only 5,100 signatures, some of which may have also been invalid.

“We are not going through this process with his petitions because we chose not to waste tax dollars,” Corson said. “We chose not to play dirty politics.”

Corson added that the campaign is ready to fight to get a few hundred dismissed signatures reinstated, saying they were tossed out in error. “We are ready to defend our petitions,” he said.

On Thursday, the board said that Brown will have to bring his campaign financial disclosures up to date by Monday. That includes an accounting of all receipts and expenditures through Aug. 10, the most recent filing deadline.

Brown had been excused from the deadline after firing his treasurer and alerting the D.C. Office of Campaign Finance to money missing from his war chest.

Mike DeBonis contributed to this report.