That's why the Coalition's convincing win in Gippsland must have come as an enormous relief for the beleaguered leader.

Not only did the National Party secure a hefty swing, it did so with the help of preferences from the Liberal Party, which ran a candidate in the seat for the first time in decades, picking up more than 20pc of the primary vote.

It's a win Nelson will be keen to spruik to his party and anyone else willing to listen as a ringing endorsement of his leadership style and his plan to cut petrol taxes.

But before Nelson supporters crack open the bubbly, several things are worth considering.

First, Gippsland has been in National Party (or Country Party) hands continuously since the First World War. It has not been a Liberal seat since 1914. Although the Liberal candidate, Rohan Fitzgerald, did manage to bleed a substantial number of votes away from Labor, it was a Nationals, not a Liberal, win.

Second, in country seats - so it is said - having a good local candidate counts for a lot more than in city seats. The Nationals' Darren Chester, a former journalist and political staff member, is a well-liked local who ran what might be described as a strong grass-roots campaign.

The Labor candidate, Darren McCubbin, ran a campaign tainted by news that he did not join the party until the day before he was nominated.

Third, high petrol prices probably played an unusually large role, as did concerns about the impact of the Government's emissions trading scheme. Nelson will not be able to rely on the same impact nationwide.

The Nationals' convincing win is a slap in the face for Kevin Rudd, but it will prove a glancing blow. And anyway, by-elections often deliver a slap in the face for incumbent governments. The real test will come in the Adelaide hills seat of Mayo, following the imminent retirement of Alexander Downer.

If nothing else, the Nationals' victory in Gippsland will allow Nelson to breathe slightly easier over the winter break.