WHEN Vincent Gray ran for mayor of Washington, DC, in 2010, he was seen as an honest alternative to Adrian Fenty, the incumbent, who was accused of cronyism. “He’ll be a leader we can trust,” Mr Gray’s campaign promised. And the voters believed it, handing him a ten-point victory over Mr Fenty in the all-important Democratic primary.

Many now feel their trust has been betrayed. According to prosecutors, Mr Gray’s efforts in 2010 were helped by a massive “shadow campaign” funded by a city contractor, so far unnamed by prosecutors. The scandal came to light earlier this month when Jeanne Clarke Harris, a public-relations consultant, admitted funnelling over $650,000 of the businessman’s money through her own companies to support Mr Gray secretly.

The prosecutors have not accused the mayor of knowing about the scheme, but they do believe the illegal effort was co-ordinated with members of his campaign. Despite raising $2.8m for the race, with only two weeks left before the primary Mr Gray had been mightily outspent by Mr Fenty, who still held a considerable cash advantage.

Prosecutors say that this was when the shadow campaign kicked into gear, lavishing funds on consultants, get-out-the-vote efforts and items, like T-shirts and yard signs, bearing the logo of the official Gray campaign.

Its impact is difficult to measure retroactively. Most polls showed Mr Gray with a lead throughout the race, and his margin of victory was substantial. (Old-timers will recall that Richard Nixon won his re-election in 1972 by a landslide—yet that was no defence against evidence of his lackeys’ “plumbing” at the Watergate hotel.) Voters’ sentiments may also have been skewed by other bits of electoral malpractice. The campaign misreported at least $100,000 in expenses to election officials, says its treasurer. In May two of Mr Gray’s aides admitted paying a minor mayoral candidate named Sulaimon Brown to stay in the race and attack Mr Fenty. Mr Brown was subsequently given a job in the administration, though Mr Gray says there was no quid pro quo. Still, his administration has been accused of nepotism and cronyism over the hiring of children of senior officials and an unqualified campaign supporter.

In the past the mayor has denied running a corrupt campaign, claiming ignorance of his aides’ misdeeds. But now he is keeping mum. Many wonder how a man with a reputation for thoroughness could have been left in the dark on these matters. Others are more sceptical. David Catania, a District council member, says it is hard to believe that a businessman would invest so much in a shadow campaign and not tell the beneficiary. Mr Catania is one of three council members, out of 12, to have called for the mayor’s resignation.

If Mr Gray were to step down, he would be replaced by Phil Mendelson, the acting council chairman; Mr Mendelson would be the city’s first white mayor since home rule was introduced in 1973. Mr Mendelson was elected chairman after his predecessor, Kwame Brown, resigned and pleaded guilty to bank fraud and campaign violations in June. Earlier in the year another council member pleaded guilty to stealing official funds and falsifying tax returns. The rot, it seems, runs right through the District’s government.

Meanwhile the investigation into the shadow campaign continues, and looks likely to net some big fish soon. The District’s next mayoral election will no doubt feature more talk of restoring integrity to the city’s government.