SOME politicians seem to be blessed with a non-stick coating that prevents scandal from attaching itself to them. Sooner or later, most of them find that the Teflon rubs off. For Stephen Harper, the Conservative prime minister of Canada, that moment may have arrived on May 15th with the news that his chief of staff, Nigel Wright, wrote a personal cheque for C$90,172 ($87,240) to clear the allegedly fraudulent expense claims of Mike Duffy, a Conservative senator. Since that day, Mr Harper has been grilled relentlessly by the opposition parties and the media about what he knew and when he knew it. Neither the passage of time nor Mr Wright’s resignation on May 19th has dulled the attack. A poll on May 31st showed that only 13% of Canadians believe Mr Harper’s repeated claims that he knew nothing of Mr Wright’s gift until it made the news. Two-thirds considered the episode an ethical breach—bad news for the Conservatives, who sold themselves as a clean alternative to the scandal-plagued Liberals they replaced. Those same Liberals are now ahead of both the Conservatives and the New Democratic Party (NDP) in opinion polls. Mr Harper has sailed through similar tempests in the past with barely a knock to his popularity or the standing of the Conservative Party. He persuaded the governor-general to close parliament twice: once in 2008 when his then-minority government was in danger of collapsing, and again the following year when he and his ministers were under fire for covering up evidence that Canada knew detainees turned over to Afghan authorities were likely to be tortured. Yet the Conservatives still won a majority in the 2011 election. Why is the latest scandal sticking when previous ones were so easily wiped away? Some of the answer lies with the prime minister’s history of centralising power in his office (a complaint also made about many of his predecessors) and of putting his personal mark on government. Departments have been told to use “The Harper Government” instead of “The Government of Canada” on news releases. The content is vetted by the Privy Council Office, the prime minister’s department, before the releases are sent out. The downside of this branding is that Mr Harper finds it difficult to distance himself when something goes wrong.

Unlike the prorogation controversies, which were too arcane to elicit a gut reaction from the man in the street, the expenses affair is easy to understand and to condemn. When your correspondent was asked by the local handyman in a small Quebec village about the affair, it was clear the story had travelled well beyond the parliamentary precincts.

Within those precincts it is being kept alive by the opposition parties, which have cast aside their windy discourses to ask brief, pointed questions, and by parliamentary reporters, who have recovered some of their confidence after being cowed by Mr Harper. Thomas Mulcair, the leader of the NDP, sounded more like a prosecutor than a politician in his exchanges with the prime minister during Question Period. Even though Canadian reporters were allowed only one question at a joint press conference held by Mr Harper and the visiting president of Chile on May 30th, the matter of the C$90,000 cheque was raised.

Brazening it out, a successful tactic in the past, has not worked for the prime minister so far. Shutting down parliament is not an option until the 2013 budget is passed by the Commons, which is expected later this month. The expense claims of Pamela Wallin, another senator appointed by Mr Harper, are still under scrutiny. When that investigation is complete it may breathe new life into the story. Unlike past controversies, the Senate expenses scandal looks set to stick around for some time.