Former French President Nicolas Sarkozy was to be questioned by investigating magistrates on Tuesday about a long-running scandal over his 2012 campaign finances. It was not clear if Sarkozy, who is maneuvering for another run at the presidency in 2017, would be charged after the session with the magistrates in Paris. The magistrates are investigating allegations of false accounting during his failed election campaign four years ago that allowed him to greatly exceed spending limits. The case hinges on the activity of PR firm Bygmalion which organised some of Sarkozy's campaign appearances and is accused of a vast system of false accounting. Bygmalion is accused of charging 18.5 million euros ($21 million) to Sarkozy's right-wing party — then called the UMP, but since renamed The Republicans — instead of the campaign, allowing it to exceed the spending limit of 22.5 million euros. Several employees at Bygmalion, including the company's accountant as well as a leading member of Sarkozy's campaign team, have admitted to the existence of the fraud, though none have accused the former president of knowing about it. Sarkozy, 61, who led France from 2007 before losing to Socialist Francois Hollande in 2012, has always denied any knowledge of the false accounting. He said he was retiring from politics after the election but made a comeback just two years later, returning to lead The Republicans and lining himself up for party primaries this autumn in a bid to contest the presidential election in May 2017. The path back to power has been far rockier than expected for Sarkozy, who is embroiled in several corruption scandals, and has failed to excite much popular support. He trails center-right rival Alain Juppe by a considerable margin in opinion polls. Sarkozy's ambitions have not been helped by the campaign financing scandal, which has recently widened beyond the activities of Bygmalion. Despite his adamant denials, the investigation has found that Sarkozy asked for more campaign events in mid-March 2012, around two months before the vote. His campaign director, Guillaume Lambert, has told police he warned Sarkozy at the time of the risk of breaching financing limits. Questioned by police in September 2015, Sarkozy said he did not remember the warning, and described the controversy as a "farce," putting the responsibility squarely on Bygmalion and the UMP. Since then, however, the investigation has widened beyond Bygmalion and is looking into a further 13.5 million euros in campaign spending by the UMP, of which only 3.0 million was declared at the time. A total of 13 people have been charged from Bygmalion and the UMP with fraud, abuse of confidence or illegal campaign financing.