Willie Rennie, the leader of the Scottish Liberal Democrats, makes an admission and a prediction in his interview with The Herald today.

The admission is that his party has been badly damaged by its association with the Tories in government; his prediction is that much of the support lost to the LibDems since the 2010 General Election will return.

The admission is certainly true. Since 2010, the LibDems have performed poorly in the Scottish parliament elections and local elections and the most recent opinion poll for the European elections in May seems to show that nothing has changed. Indeed, the ICM poll published earlier this week had the LibDems on 5% - behind UKIP on 6%.

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Mr Rennie's take on this is that all is not lost. Yes, he says, the faith voters showed in the LibDems in 2010 has been shaken, but he believes many could return to the fold. He also believes the party's European credentials will be attractive at the polls in May and in this he has the benefit of consistency: the LibDems have always been a pro-EU party - the party of "in" as Mr Rennie puts it.

The question is whether any of this will matter in May and, longer term, whether a positive European agenda and the party's achievements at Holyrood and Westminster can counter the effect of coalition with the Tories. The frustration for the LibDems is Mr Rennie is an effective performer at Holyrood and the party has done well in pursuing issues that matter to them, most notably concerns about the single police force. And yet the Scottish allergy to Toryism, even at one removed, means there is no sign of a recovery.

This has left the LibDems in a dilemma over how to manage their relationship with the Coalition. In his interview today, ahead of the opening of the spring conference in Aberdeen, Mr Rennie defends the Coalition's record and he clearly believes the LibDems could receive some of the credit for the economy recovering - although in Scotland the risk remains they will instead be punished for the Tory policies they supported.

The LibDems have tried to counter this by claiming they have tamed the Tories and have suggested that, without Coalition, it would have been a lot worse. Students in England and Wales paying tuition fees will find that hard to swallow, but equally, the LibDems did achieve their ambition to raise the threshold at which people start to pay income tax to £10,000 - something that probably would not have happened under a Tory-only government.

The LibDems in Scotland also deserve credit for their positive campaigning in the independence debate - somewhat undermined by Danny Alexander's negative language in his speech today about Scotland being at "five minutes to midnight".

The difficult job for the party now is to continue this balancing act of claiming credit for some elements of the Coalition's work while distancing themselves from others. It will be hard to achieve, and even if they can do it, it may be too late. Mr Rennie says he believes there is a chunk of the electorate who voted LibDem in 2010 that is waiting to make an assessment of the party, but the danger is they have already made up their minds.

It may seem unfair that Mr Rennie and his Holyrood colleagues should be punished for what his party at Westminster has done but many voters will think the opposite: that it is entirely fair to punish a party for helping to deliver policies which many Scots dislike.