In addition, McGinley represents those before the FEC in connection with audits and enforcement actions.
According to McGinley's statement, "The campaign has contacted the appropriate federal authorities and is actively cooperating with their investigation. For this reason, we will not comment further on this matter at this time."
Last month, amended finance reports filed by the Republican congressman's new treasurer, Douglas Heun, show LoBiondo's campaign raised and spent less during the last two years than it had originally reported.
The reports show amounts inflated by about $277,000, but do not detail the discrepancies.
Christian Hilland, an FEC spokesman, said officials could not confirm an investigation or comment on pending matters.
LoBiondo, with a reputation as a moderate legislator, was first elected to Congress in 1994, representing the southernmost parts of New Jersey, including Atlantic and Cape May Counties. He won reelection this month.
LoBiondo has had little reason to spend money on recent campaigns, having had marginal opposition since facing former State Sen. William Gormley in the 1994 Republican primary.
In his 2010 race, Democratic opponent Gary Stein reported raising no money for the election, and LoBiondo reported having $1 million in cash on hand.
McCrosson had worked as LoBiondo's campaign treasurer since 1996 and was replaced earlier this year after being named acting business administrator for the City of Trenton. Last week, he resigned.
He did not return a message seeking comment Tuesday. The federal investigation was first reported Monday by the website PolitickerNJ.
McCrosson, who also worked at the United Way of Atlantic County, formerly served as the business administrator in Ventnor, but resigned last year after Theresa Kelly had become mayor in 2008 following a power struggle with the outgoing administration.
Ventnor Commissioner John Piatt said that 10 years of audits, citing improper record-keeping, raised concerns among the new board and that he unsuccessfully requested that the state conduct a forensic audit.
"One of the most basic things is they didn't have a master ledger," Piatt said, adding that he would welcome federal scrutiny that "may shed some light on things we've been wondering about for quite some time."
Contact staff writer Barbara Boyer at 856-779-3838 or bboyer@phillynews.com.This article contains information from the Associated Press.