Leading article: What is and isn't at stake in Oldham East

Today's by-election in Oldham East and Saddleworth is being widely presented as a crucial first test: for the Coalition, for the Liberal Democrats, and for Ed Miliband. Not surprisingly, the Liberal Democrat candidate, Elwyn Watkins, has tried to run his campaign exclusively on local issues, while his Labour opponent, Debbie Abrahams, has tried to elevate it into a referendum on the Government in general, and on Nick Clegg in particular.

All other things being equal, Mr Watkins should have cruised to victory. The reason for the by-election alone – the verdict of a special election court that banned Phil Woolas from Parliament for making false statements about his rival – should have guaranteed the Liberal Democrat a head start. Then there was the narrowness of his defeat in May, by a mere 106 votes.

But that was then and this is now. Latest opinion polls show Labour with a double-digit lead, suggesting that voters may be treating this contest as a chance to pass judgement on the Coalition. Even so, a victory for Mr Watkins cannot be completely ruled out. Liberal Democrats have a deep-rooted and well-organised presence here; voting local may still appeal, whatever people feel about Mr Clegg, and a sense that they were cheated of victory in May could be an additional galvanising factor. The Conservative candidate, Kashif Ali, trails a distant third.

If, as it appears, this turns out to be essentially a two-candidate contest, and the voting is closer than the polls indicate, all interested parties will be able to take comfort. Mr Miliband will be that bit more secure in the Labour leadership; Mr Clegg will avoid humiliation; and the Coalition will insist that it has not lost popular support. All of which suggests that this by-election is not quite as crucial as has been claimed.

Mr Miliband has only just passed his 100 days as Labour leader. A better or worse showing by the Liberal Democrats will not jeopardise the Coalition. And the next general election is not due for more than four years. The result will afford an intriguing glimpse of the lie of the political land, but any wider conclusions to be drawn might be limited.