D.C. Mayor Vincent Gray’s 2010 campaign, already the subject of an investigation that has prompted two District power brokers to plead guilty to federal charges, could soon take another hit with the release of an audit into his election spending.

The District’s Office of Campaign Finance launched a full investigative audit of the Gray campaign last year, and regulators completed a preliminary report in December that has been kept secret. After months of reviews, the audit has entered its closing stages.