Oldham and Saddleworth by-election: who has most to lose?

There was a time that prime ministers didn’t personally visit by-elections. They took the credit, or blame, but didn’t personally take the heat. That changed when Blair fought Uxbridge in 1997: now, it seems party leaders board the train almost before the writ is moved.

Hence Ed Miliband is due in Oldham & Saddleworth today, David Cameron is expected shortly, and debate rages over whether Nick Clegg should go (will eggs be thrown?) or stay (will he look frightened of egg-throwing?) And while Labour is the party with a seat to lose, the leader with most at stake on January 13 is arguably Clegg.

Theoretically, it should be a shoo-in for the Lib Dem candidate Elwyn Watkins: he was only 103 votes short in May and following a court ruling that the defending MP Phil Woolas smeared him in an election leaflet, has the moral high ground. A short campaign, hampered by Christmas and the icy weather, will hurt Labour’s Debbie Abrahams, who hasn’t stood here before and needs time to build a profile. Unfortunately for Clegg, these favourable odds mean that if Watkins does lose it will be the national leadership’s unpopularity that gets blamed, reopening debate over the toxicity of coalition.

Yet it is unfair to see this as a proxy vote on one leader, and not just because local issues too have their place. All three leaders’ national strategies are actually being roadtested here.

Like Ed Miliband, Abrahams’ task is to disown a tainted predecessor without trashing the party’s record. Her charges of broken coalition promises (echoing Miliband’s line at Prime Minister’s Questions yesterday) will be seen as a dry run for Labour’s national tactics: if she does badly, doubts over Miliband’s own strategy may intensify.

Conservative candidate Kashif Ali, meanwhile, wasn’t far behind Watkins and could benefit if Tories who usually vote tactically for the Lib Dems decide the maths has changed. Yet what will his supporters make of job losses at Greater Manchester Police, given local concerns about drug and gun crime, or today’s announcement on ending the detention of failed asylum seekers’ children? Like Cameron, Ali must beware defecting rightwingers: while the BNP gets headlines here, UKIP polled just under four per cent in Oldham in May and has been building since 2001. Perhaps the great surge north suggests bigger reputations than Woolas’ are on the line.

Gaby Hinsliff is a former Political Editor for The Observer newspaper.