The federal investigation into D.C. Mayor Vincent Gray's campaign is unlikely to conclude before summer after a federal judge postponed a hearing for a woman who helped implement the illegal, off-the-books shadow campaign that boosted Gray's prospects.

Jeanne Clarke Harris, who served as a communications consultant to Gray's 2010 campaign, was scheduled to appear in federal court for a status hearing Monday, but Judge Colleen Kollar-Kotelly agreed to delay it until March because prosecutors said they weren't ready to set a sentencing date. The postponement means it's unlikely Harris, who was charged with fraud, conspiracy and a campaign finance count, will face sentencing before June.

In a written motion, Harris' lawyer, Mark Tuohey, wrote that his client had "cooperated fully with the government."

Although she was the third person linked to Gray's campaign charged in connection to the probe, Harris' case is perhaps the most critical to the future of the investigation.

According to court papers, Harris helped implement a $653,800 shadow campaign that was intended to prop up Gray's citywide bid against Adrian Fenty, the incumbent mayor.

While Harris played a significant role in the execution of the shadow campaign, she was not responsible for designing or funding the secret operation.

"The money was from co-conspirator No. 1, but the plan was developed by another person," Harris said in July.

People familiar with the investigation have identified co-conspirator No. 1 as Jeffrey Thompson, a major city contractor. He has not been charged, and his attorney has declined to comment.

According to prosecutors, Harris and her co-conspirator also ran a straw donations scheme under which the co-conspirator made donations to local and federal candidates in the names of 19 people and companies.

The ruling in the Harris case marked the second time in a week that Kollar-Kotelly approved plans that will extend the life of the nearly 2-year-old investigation.

Last week, Kollar-Kotelly sided with prosecutors when she overruled a request from Thomas Gore, the campaign's assistant treasurer, to schedule sentencing in his case. Gore pleaded guilty to obstruction of justice and three local campaign finance charges.SClBThe Gore case, however, is related to a matter separate from the shadow campaign, though both his case and Harris' are part of the larger probe of Gray's campaign.

Gray has denied wrongdoing and vowed to complete his term, which ends in January 2015. He has not said whether he will seek re-election.